ARTICLE | doi:10.20944/preprints201810.0702.v1
Subject: Social Sciences, Other Keywords: Andean microalgae consumption; Atacama; cyanobacteria; Llayta; microethnography; Nostoc
Online: 30 October 2018 (04:43:02 CET)
Llayta is a dietary supplement used by rural communities in Perú and northern Chile since pre-Columbian days. Llayta is the biomass of colonies of a Nostoc cyanobacterium grown in wetlands of the Andean highlands, harvested, sun-dried and sold as an ingredient for human consumption. The biomass has a substantial content of essential amino acids (58% of total amino acids) and polyunsaturated fatty acids (33% total fatty acids). This ancestral practice is being loss and the causes were investigated by an ethnographic approach to register the social representations of Llayta, to document how this Andean feeding practice is perceived and how much the community knows about Llayta. Only 37% of the participants (mostly adults) have had a direct experience with Llayta; other participants (mostly children) did not have any knowledge about it. These social responses reflect anthropological and cultural tensions associated to lack of knowledge on Andean algae, sites where to find Llayta, where it is commercialized, how it is cooked and on its nutritional benefits. The loss of this ancestral feeding practice, mostly on northern Chile, is probably associated to cultural changes, migration of the rural communities, and a very limited access to the available information. We propose that Llayta consumption can be revitalized by developing appropriate educational strategies and investigating potential new food derivatives based on the biomass from the isolated Llayta cyanobacterium.
ARTICLE | doi:10.20944/preprints201911.0108.v1
Subject: Earth Sciences, Environmental Sciences Keywords: microalgae; cyanobacteria; biomass composition; culture optimization; growth on wastewaters
Online: 10 November 2019 (10:56:59 CET)
The purpose of this work is to define optimal growth conditions for batch culture of the cyanobacterium Arthrospira maxima and the microalgae Chlorella vulgaris, Isochrysis galbana and Nannochloropsis gaditana. Thus, we study the effect of three variables on algae growth: i.e., inoculum:culture medium ratio, light:darkness photoperiod and type of culture medium, including both synthetic media and wastewaters. The results showed that the initial inoculum volume did not affect the amount of biomass at the end of the growth (14 days), whereas an excess (18 h) or defect (6 h) in the number of hours of light is determinant for its development. The contribution of nutrients from different culture media modified the growth of the different species. A. maxima was favoured in seawater enriched with Guillard's F/2 as well as C. vulgaris and N. gaditana but in fresh water medium. I. galbana had the greatest growth in the marine environment enriched with Walne’s media. Nitrate was the limiting growth reagent at the end of the exponential phase of growth for C. vulgaris and N. gaditana, while iron was for A. maxima and I. galbana. All species demonstrated their capability to grow in effluents from a wastewater treatment plant and they efficiently consume nitrogen, especially the three microalgae species.
REVIEW | doi:10.20944/preprints202008.0233.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: lignocellulosic substrate; pre-treatment; microalgae/cyanobacteria; biogas; problems; animal feed
Online: 10 August 2020 (03:46:14 CEST)
Modern day civilization is dependent on energy generation by fossil fuels. But the major drawback of using fossil fuels is environmental pollution. Microalgae are potential candidate for production of various products of interest, such as proteins, mini food, pigments and triglycerides that can be converted into biofuels. Lignocellulosic feedstocks are the most abundantly available raw material of plants that can serve as a promising feedstock for cultivating bacteria, fungi, yeasts and microalgae to produce biofuels and other value-added products. Owing to the abundant availability of these low/no cost substrates, can be utilized as feedstocks for cultivating microalgae to generate biogas/biodiesel. Likewise, there is much room to exploit defatted algal biomass to be used as animal/fish feed and oil producing/accumulating genes knowledge in future to produce high and good quality biodiesel and biogas.
ARTICLE | doi:10.20944/preprints202206.0016.v1
Subject: Life Sciences, Molecular Biology Keywords: lipids; regulation; microalgae; transcription factors
Online: 1 June 2022 (11:09:11 CEST)
Microalgae biomass is considered a promising alternative feedstock for biodiesel production due to its high productivity of neutral lipids, specially under abiotic stress conditions. Among the unicellular microalgae that show this characteristic, Chlamydomonas reinhardtii appears as one of the most important model species that have increased lipids production under abiotic stress conditions. In this study, we show that cells cultivated under mixotrophic condition supplemented with 0.1 M of NaCl rapidly raises their amount of neutral lipids in C. reinhardtii without reduction of their cellular growth rate, being therefore a promising condition for biomass towards bioenergy production. The nuclear proteome of these cells was investigated where we identified 323 proteins with an enrichment of almost 60% of nuclear proteins in the total dataset. We found 61 proteins differentially regulated upon salt treatment, including proteins annotated in functional categories related to translation and nucleosome assembly functions, among others. Additionally, we identified Transcription factor proteins (TFs) and analyzed their likely Transcription factors-binding regulatory elements identifying target genes related to lipids metabolism and kinase functions, indicating possible regulatory pathways of lipids biosynthesis. Together these data can help understand regulatory nuclear mechanisms leading to an increase of lipids in the first 24h of salt stress 0.1M NaCl.
ARTICLE | doi:10.20944/preprints201704.0085.v1
Subject: Life Sciences, Biotechnology Keywords: lipid extracted microalgae, isoprenoids, detoxification
Online: 14 April 2017 (09:11:15 CEST)
Microalgae are recognized as a third generation feedstock for biofuel production due to its rapid growth rate and lignin-free characteristic. In this study, the lipid extracted microalgae biomass residues was used as the material to produce isoprene, α-pinene and β-pinene with the engineered E. coli strain. We adopted an optimal sulfuric acid hydrolysis method to convert holocellulose into fermentable sugar efficiently (6.37 g/L) and explored a novel detoxification strategy (phosphoric acid/calcium hydroxide) to remove inhibitors notably. 55.32 % acetic acid, 99.19 % furfural and 98.22 % 5-HMF were cut down with the phosphoric acid/calcium hydroxide method, and the fermentation concentration of isoprene (223.23 mg/L), α-pinene (382.21 μg/L) and β-pinene (17.4 mg/L) using the detoxified hydrolysate as the carbon source account for approximately 86.02 %, 90.16 % and 88.32 % of those produced by the engineered E. coli strain fermented on pure glucose, respectively.
Subject: Life Sciences, Biochemistry Keywords: cyanobacteria; heterocyst; regulation of differentiation
Online: 2 November 2020 (15:32:02 CET)
The filamentous cyanobacterium Anabaena sp. PCC 7120 expresses during the differentiation of heterocysts a short peptide PatS and a protein HetN, both containing an RGSGR pentapeptide essential for activity. Both act on the master regulator HetR to guide heterocyst pattern formation by controlling the binding of HetR to DNA and its turnover. A third small protein, PatX, with an RG(S/T)GR motif is present in all HetR-containing cyanobacteria. In nitrogen-depleted medium, inactivation of patX does not produce a discernible change in phenotype, but its overexpression blocks heterocyst formation. Mutational analysis revealed that PatX is not required for normal intercellular signaling, but it nonetheless is required when PatS is absent to prevent rapid ectopic differentiation. Deprivation of all three negative regulators – PatS, PatX, and HetN – resulted in synchronous differentiation. However, in nitrogen-containing medium, such deprivation leads to extensive fragmentation, cell lysis, and aberrant differentiation, while either PatX or PatS as the sole HetR regulator can establish and maintain a semiregular heterocyst pattern. These results suggest that tight control over HetR by PatS and PatX is needed to sustain vegetative growth and regulated development. The mutational analysis has been interpreted in light of the opposing roles of negative regulators of HetR and the positive regulator HetL. Keywords: cyanobacteria; heterocyst, regulation of differentiation
REVIEW | doi:10.20944/preprints202012.0658.v1
Subject: Life Sciences, Biochemistry Keywords: microalgae; industries; manufacturers; isolation; bioactive compounds; microalgae products; nutraceuticals; pharmaceutical; cosmeceutical; biofuels; biofertilizer; wastewater treatment
Online: 25 December 2020 (12:55:27 CET)
Microalgae are known as a rich source of bioactive compounds which exhibit different biological activities. Increased demand for sustainable biomass for production of important bioactive components with various potential especially therapeutic applications has resulted in noticeable interest in algae. Utilization of microalgae in multiple scopes has been growing in various industries ranging from harnessing renewable energy to exploitation of high-value products. The focuses of this review are on the isolation of bioactive compounds from microalgae regarding different metabolites which are currently used and new possible applications of the compounds in industries and future prospects. Moreover, this work discusses the advantage, potential new beneficial strains, applications, limitations, research gaps and future prospect of microalgae in industry.
ARTICLE | doi:10.20944/preprints201902.0017.v1
Subject: Chemistry, Chemical Engineering Keywords: FAEEs; biodiesel; mixed biocatalysts; lipases; microalgae
Online: 2 February 2019 (03:23:32 CET)
The production of fatty acids ethyl esters (FAEEs) to be used as biodiesel from oleaginous microalgae shows great opportunities as an attractive source for the production of renewable fuels without competing with human food. To ensure the economic viability and environmental sustainability of the microbial biomass as a raw material, the integration of its production and transformation into the biorefinery concept is required. In the present work, lipids from wet Isochrysis galbana microalga were extracted with ethyl acetate with and without drying the microalgal biomass (dry and wet extraction method, respectively). Then, FAEEs were produced by lipase-catalyzed transesterification and esterification of the extracted lipids with ethanol using lipase B from Candida antarctica (CALB) and Pseudomonas cepacia (PC) lipase supported on SBA-15 mesoporous silica functionalized with amino groups. The conversion to FAEEs with CALB (97 and 85.5 mol% for dry and wet extraction, respectively) and PS (91 and 87 mol%) biocatalysts reached higher values than those obtained with commercial Novozym 435 (75 and 69.5 mol%). Due to the heterogeneous nature of the composition of microalgae lipids, mixtures with different CALB:PC biocatalyst ratio were used to improve conversion of wet-extracted lipids. The results showed that a 25:75 combi-lipase produced a significantly higher conversion to FAEEs (97.2 mol%) than those produced by each biocatalyst independently from wet-extracted lipids and similar ones than those obtained by each lipase from the dry extraction method. Therefore, that optimised combi-lipase biocatalyst, along with achieving the highest conversion to FAEEs, would allow improving viability of a biorefinery since biodiesel production could be performed without the energy-intensive step of biomass drying.
Subject: Life Sciences, Biochemistry Keywords: Cyanobacteria; Gene expression; Regulation; Signalling; Stress
Online: 23 October 2020 (12:26:14 CEST)
Cyanobacteria are highly diverse, widely distributed photosynthetic bacteria inhabiting various environments ranging from deserts to the cryosphere. Throughout this range of niches, they have to cope with various stresses and kinds of deprivation which threaten their growth and viability. In order to adapt to these stresses and survive, they have developed several global adaptive responses which modulate the patterns of gene expression and the cellular functions at work. Sigma factors, two-component systems, transcriptional regulators and small regulatory RNAs acting either separately or collectively, for example, induce appropriate cyanobacterial stress responses. The aim of this review is to summarize our current knowledge about the diversity of the sensors and regulators involved in the perception and transduction of light, oxidative and thermal stresses and nutrient starvation responses. The studies discussed here point to the fact that various stresses affecting the photosynthetic capacity are transduced by common mechanisms.
REVIEW | doi:10.20944/preprints201910.0034.v1
Subject: Life Sciences, Other Keywords: microcystin; cyanobacteria; cyanotoxin; structural elucidation; toxicology
Online: 3 October 2019 (03:43:55 CEST)
Hepatotoxic microcystins (MCs) are the most widespread class of cyanotoxins and the one that has most often been implicated in cyanobacterial toxicosis. One of the main challenges in studying and monitoring MCs is the great structural diversity within the class. The full chemical structure of the first MC was elucidated in the early 1980s and since then the number of reported structural analogues has grown steadily and continues to do so, thanks largely to advances in analytical methodology. The structures of some of these analogues have been definitively elucidated after chemical isolation using a combination of techniques including nuclear magnetic resonance, amino acid analysis and tandem mass spectrometry (MS/MS). Others have only been tentatively identified using liquid chromatography-MS/MS without chemical isolation. An understanding of the structural diversity of MCs, the genetic and environmental controls for this diversity and the impact of structure on toxicity are all essential to the ongoing study of MCs across several scientific disciplines. However, because of the diversity of MCs and the range of approaches that have been taken for characterizing them, comprehensive information on the state of knowledge in each of these areas can be challenging to gather. We have conducted an in-depth review of the literature surrounding the identification and toxicity of known MCs and present here a concise review of these topics. At present, at least 269 MCs have been reported. Among these, about 20% (54 of 269) appear to be the result of chemical or biochemical transformations of MCs that can occur in the environment or during sample handling and extraction of cyanobacterial, including oxidation products, methyl esters, or post-biosynthetic metabolites. The toxicity of many MCs has also been studied using a range of different approaches and a great deal of variability can be observed between reported toxicities, even for the same congener. This review will help clarify the current state of knowledge on the structural diversity of MCs as a class and the impacts of structure on toxicity, as well as to identify gaps in knowledge that should be addressed in future research.
ARTICLE | doi:10.20944/preprints201801.0027.v1
Subject: Chemistry, Organic Chemistry Keywords: microginins; cyanobacteria; Microcystis; aminopeptidase M inhibitors
Online: 5 January 2018 (04:16:23 CET)
During blooms, cyanobacteria produce diverse modified peptides. Among these are the microginins, which inhibit zinc-containing metalloproteases. Ten microginins, microginins KR767 (1), KR801(2), KR835 (3), KR785 (4), KR604 (5), KR638 (6), KR781 (7), KR815 (8), FR3 (9), and FR4 (10) were isolated from the extract of a bloom material of Microcystis sp. (IL-405) collected from the Kishon Reservoir, Israel in the fall of 2009. The structures of the pure compounds were elucidated using 1D and 2D NMR techniques and high-resolution mass spectrometry. The absolute configuration of the chiral centers of the amino acids were determined by Marfey’s and advance Marfey’s methods and by comparison of 1H and 13C NMR chemical shifts of the Ahda derivatives with those of known microginins. These microginins differ in sequence and absolute configuration of the chiral centers of the Ahda moieties and by N-methylation of Ahda amine group and extent of chlorination of Ahda terminal methyl group. The compounds were evaluated for inhibition of the zinc metalloprotease aminopeptidase M and exhibited low- to sub-nanomolar IC50 values.
ARTICLE | doi:10.20944/preprints202211.0284.v1
Subject: Life Sciences, Biotechnology Keywords: microalgae; biomass; photosynthesis; mixotrophic; LC-MS/MS
Online: 15 November 2022 (09:54:52 CET)
NH4Cl is one of the nitrogen sources for microalgal cultivation. However, excessive amounts of NH4Cl affects microalgal physiology and biomass contents. In this study, the effects of ammonium on microalgal growth and TAG content in the green microalga (Chlamydomonas reinhardtii) was investigated. Microalgal growth and TAG content under photoautotrophic conditions were found to be unchanged with 17 mM of ammonium, while this compound interfered with microalgal growth and induced TAG content under mixotrophic conditions with acetate supplementation. This suggested that ammonium could induce TAG production when acetate occurred in microalgal cultivation. Further, the effects of two different concentrations of NH4Cl (17 mM and 60 mM) on the cells under mixotrophic conditions were investigated. The results showed that both concentrations reduced microalgal growth, but induced total lipid and TAG content, especially after a 4-day cultivation. The oxygen evolution and Fv/Fm ratio showed that both concentrations completely inhibited the oxygen evolution on Day 4. The 60 mM NH4Cl reduced the Fv/Fm ratio from 0.7 to 0.48 indicating that ammonium supplementation directly affects the microalgae photosynthesis performance. A total of 1782 proteins were successfully identified using proteomics analysis. Among them, there were nine overexpressed proteins and four proteins were underexpressed. Using the protein–ligand interaction analysis, nitrogen metabolism is involved under NH4Cl conditions. This information can provide biochemical knowledge for microalgae development for sustainable energy usage.
REVIEW | doi:10.20944/preprints202110.0390.v1
Subject: Life Sciences, Biotechnology Keywords: Biological contaminants; grazers; microalgae; open cultivation; biopesticides
Online: 26 October 2021 (14:36:19 CEST)
Microalgae biomass is a budding raw material for the origination of food, fuel, and other value-added products. However, bulk production of microalgal biomass at commercial level is a herculean task for the current microalgal mass production technologies due to the undesirable contaminations by biological pollutants. These contaminants hamstring the production of microalgae biomass by debilitating the growth of cultures, crumble the quality of biomass and sometimes may crash the whole culture. The best utilization of the microalgae biomass at industrial level could be attained by avoiding various possible biological contaminations in mass cultivation system, understanding the contamination mechanisms, and the complex interactions of algae with other microorganisms. This review explores the various types of biological pollutants, their possible mode of infection along with mechanisms, different controlling methods to maintain desired microalgae culture.
REVIEW | doi:10.20944/preprints201912.0377.v1
Subject: Life Sciences, Microbiology Keywords: algae; wastewater; microalgae; biofuels; phytoplankton; aquaculture; phycology
Online: 29 December 2019 (09:34:40 CET)
Microalgae wastewater treatment has long been promoted as a sustainable method to handle the influx of human waste due to population growth. Initially, in the early 1900’s, microalgae was noted to increase wastewater treatment efficiency by aerating the water and consuming waste. By mid-century, wastewater grown microalgae was being investigated as a way to produce biomass for food, fuel, and other biomaterials. The space race in the 1960’s led to the use of microalgae in life support systems. Technological developments and political pressure in the 1970’s spurred studies of the impact of wastewater on the growth of phytoplankton in the oceans as well as methods to use microalgae wastewater treatment in aquaculture. Simultaneously, the oil crisis of that decade promoted research of alternative fuels, which included microalgae biofuels via the Aquatic Species Program. This program led to research into the use of wastewater as a feedstock for microalgae growth. By the later 2000’s, instability in the oil market caused another energy crisis which further prompted investment in microalgae biofuels, some of which involved combined wastewater treatment. Currently, microalgae wastewater treatment is being researched as a way to cut back on greenhouse gas emissions to curb global warming and produce sustainable biofuels.
ARTICLE | doi:10.20944/preprints202209.0219.v1
Subject: Biology, Other Keywords: cyanobacteria; cyanosphere; heterotroph bacteria; metagenomics; functional redundancy
Online: 15 September 2022 (04:11:18 CEST)
Cyanobacteria constitute pioneer colonizer of specific environments whom settlement in new biotopes precedes the establishment of composite microbial consortia. Some heterotrophic bacteria constitute cyanobacterial partners that are considered as their cyanosphere, being potentially involved in mutualistic relationships through exchange and recycling of key nutrients, and sharing of common goods. Several non-axenic cyanobacterial strains have been recently isolated along with their associated cyanosphere from the thermal mud of Balaruc-les-Bains (France) and the biofilms of the retention basin where they develop. The community structure and relationships among members of the isolated cyanobacterial strains were characterized using a metagenomic approach combined with taxonomic and microscopic description of the microbial consortia. Results provide insights into the potential role and metabolic capabilities of microorganisms of thermal mud-associated cyanobacterial biofilms. Thus, the physical proximity, host-specificity and complimentary functions advocate for their complementarity between cyanobacteria and their associated microbiota. Besides these findings, our results also highlight the great influence of the reference protein database chosen when performing functional annotation of the metagenomes from organisms of the cyanosphere and the difficulty of selecting one unique database that appropriately cover both autotroph and heterotroph metabolic specificities.
ARTICLE | doi:10.20944/preprints202204.0112.v1
Subject: Biology, Ecology Keywords: Cyanobacteria; Chlorophyll d; acaryochloris; NIR; photosynthesis; stromatolite
Online: 12 April 2022 (11:59:49 CEST)
Abstract: The genus Acaryochloris is unique among phototrophic organisms due to the dominance of chlorophyll d in its photosynthetic reaction centres and light-harvesting proteins. This allows Acaryochloris to capture light energy for photosynthesis over an extended spectrum of up to ~760 nm in the near infra-red (NIR) spectrum. Acaryochloris sp. has been reported in a variety of ecological niches, ranging from polar to tropical shallow aquatic sites. Here, we report a new Acarychloris strain isolated from an NIR-enriched stratified microbial layer 4-6 mm under the surface of stromatolite mats located in the Hamelin Pool of Shark Bay, Western Australia. Pigment analysis, by traditional spectrometry/fluorometry, flow cytometry and spectral confocal microscopy identify unique patterns in pigment distribution that likely reflect niche adaption. For example, unlike the original A. marina species (type strain MBIC11017), this new strain, Acarychloris LARK001, shows little change in the chlorophyll d/a ratio in response to changes in light wavelength, displays a different Fv/Fm response and lacks detectable levels of phycocyanin. Indeed, 16S rRNA analysis supports the identity of the A. marina LARK001 strain as distinct from the A. marina HICR111A strain first isolated from Heron Island, previously found on the Great Barrier Reef, under coral rubble on the reef flat. Taken together, A. marina LARK001 is a new cyanobacterial strain adapted to the stromatolite matts in Shark Bay.
ARTICLE | doi:10.20944/preprints202202.0189.v1
Subject: Life Sciences, Microbiology Keywords: cyanosphere; cyanobacteria; Llayta; Nostoc macrocolonies; metagenomics; microbiome
Online: 15 February 2022 (20:25:40 CET)
Cyanobacteria biomasses are sources of secondary metabolites and nutritious ingredients such as vitamins, essential amino acids, and unsaturated fatty acids. Biochemical composition, presence of cyanotoxins and contaminants are major concerns to be addressed on such edible biomasses. Macrocolonies of a filamentous diazotrophic Nostoc species known as Llayta are found at Andean wetlands and consumed since pre-Columbian times in South America. Its biochemical composition has been previously conducted to assess their nutritious quality and cyanotoxicity. Macrocolonies of filamentous cyanobacteria are niches for colonization by diverse microorganisms; however, the Llayta microcolonies cyanosphere is unknown. Based on a culture-independent approach, we report the identification of members of the resilient microflora associated with Llayta trichomes after Gentamicin treatments. We have also reconstructed the genomes of the Llayta macrocolony-forming Nostoc sp. cyanobacterium (6,781,030 bp; GC content of 41.2%) and the genomes of five dominant bacteria genera (Mesorhizobium, Microvirga, Paracoccus, Aquimonas, and Blastomonas). The detection of genes and genes clusters involved in primary and secondary metabolism is described. Our results provide new insights on the metabolic capabilities and biotechnological potential of the Andean Nostoc cyanobacterium, and the ecological role and adaptive strategies of microorganisms living under extreme environmental conditions at the Andean wetlands.
ARTICLE | doi:10.20944/preprints202105.0680.v1
Subject: Biology, Anatomy & Morphology Keywords: Protists; cyanobacteria; rotifers; crustacea; hypersalinity; Messolonghi saltworks
Online: 27 May 2021 (14:17:02 CEST)
During a survey in 2015 an impressive assemblage of organisms were found in a hypersaline pond of the Messolonghi saltworks. The salinity ranged between 50 and 180 ppt and the organisms recorded fell in the categories of Cyanobacteria (17 species), Chlorophytes (4 species), Diatoms (23 species), Dinoflagellates (1 species), Protozoa (40 species), Rotifers (8 species), Copepods (1 species), Artemia sp., one nematode and Alternaria sp. (Fungi). Fabrea salina was the most prominent protist in all samples and salinities. This ciliate has the potential to be a live-food candidate for marine fish larvae. Asteromonas gracilis proved a sturdy microalga performing excellently in a broad spectrum of culture salinities ies. Most of the specimens were identified only to the genus level and, based on their morphology, as there are no relevant records in Greece, there is a possibility for some of them to be either new species or strikingly different strains of certain species recorded elsewhere.
ARTICLE | doi:10.20944/preprints201906.0310.v1
Subject: Life Sciences, Microbiology Keywords: cyanobacteria; secondary metabolite; genome mining; molecular networking
Online: 30 June 2019 (10:42:22 CEST)
Cyanobacteria are an ancient lineage of slow-growing photosynthetic bacteria and a proliﬁc source of natural products with diverse chemical structures and potent biological activities and toxicities. The chemical identiﬁcation of these compounds remains a major bottleneck. Strategies that can prioritize the most proliﬁc strains and novel compounds are of great interest. Here, we combine chemical analysis and genomics to investigate the chemodiversity of secondary metabolites based on their pattern of distribution within some cyanobacteria. Planktothrix being a cyanobacterial genus known to form blooms worldwide and to produce a broad spectrum of toxins and other bioactive compounds, we applied this combined approach on four closely related strains of Planktothrix. The chemical diversity of the metabolites produced by the four strains was evaluated using an untargeted metabolomics strategy with high-resolution LC-MS. Metabolite proﬁles were correlated with the potential of metabolite production identified by genomics for the different strains. Although, the Planktothrix strains present a global similarity in term biosynthetic cluster gene for microcystin, aeruginosin and prenylagaramide for example, we found remarkable strain-specific chemo-diversity. Only few of the chemical features were common to the four studied strains. Additionally, the MS/MS data were analyzed using Global Natural Products Social Molecular Networking (GNPS) to identify molecular families of the same biosynthetic origin. In conclusion, we present an efﬁcient integrative strategy for elucidating the chemical diversity of a given genus and link the data obtained from analytical chemistry to biosynthetic genes of cyanobacteria.
ARTICLE | doi:10.20944/preprints201906.0043.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: microalgae; photobioreactor; flashing light effect; Computational Fluid Dynamics
Online: 5 June 2019 (14:56:44 CEST)
In a thin-volume photobioreactor where a concentrated suspension of microalgae is circulated throughout the established spatial irradiance gradient, microalgal cells experience a time-variable irradiance. Deploying this feature is the most convenient way of obtaining the so-called “flashing light” effect, improving biomass production in high irradiance. This work investigates the light flashing features of sloping wavy photobioreactors, a recently proposed type, by introducing and validating a Computational Fluid Dynamics model. Two characteristic flow zones (straight top-bottom stream and local recirculation stream), both effective toward light flashing, have been found and characterised: a recirculation-induced frequency of 3.7 Hz and straight flow-induced frequency of 5.6 Hz were estimated. If the channel slope is increased, the recirculation area becomes less stable while the recirculation frequency is nearly constant with flow rate. The validated CFD model is a mighty tool that could be reliably used to further increase the flashing frequency by optimising the design, the dimensions, the installation and the operational parameters of the sloping wavy photobioreactor.
ARTICLE | doi:10.20944/preprints202107.0444.v1
Subject: Biology, Anatomy & Morphology Keywords: cyanobacteria; Phormidium; culture growth; light; salinity; phycocyanin; pigments
Online: 20 July 2021 (11:35:05 CEST)
A strain of the filamentous non N-fixing cyanobacterium Phormidium sp. isolated from the Messolonghi (W. Greece) saltworks, was cultured in the laboratory at 6 different combinations of salinity (20-40-60 ppt) and illumination (low-2000 lux and high-8000 lux). At salinities of 60 and 40 ppt and in high illumination (XL-8000 lux) the growth rate (μmax) presented the highest values (0.491 and 0.401 respectively) compared to the corresponding at 20 ppt (0.203). In general and at all salinities, the higher illumination (XL) gave the highest growth rates and shorter dublication time (tg) in comparison to the lower illumination (L). On the contrary, phycocyanin, phycoerythrin and allophycocyanin production was extremely increased in the lower illumination (L) in all salinities, from ~14fold at 40 and 60 ppt to 269fold at 20 ppt of those corresponding to higher illumination (XL). Similar analogies were also recorded for the other two billiproteins. Chlorophyll-a content was also higher in lower illumination at all salinities in contrast to total carotenoids that did not exhibit such a pattern. The high growth rate and high phycocyanin content along with the rapid sedimentation of its cultured biomass can set this marine Phormidium species as a promising canditate for mass culture.
REVIEW | doi:10.20944/preprints202105.0232.v1
Subject: Biology, Ecology Keywords: cyanobacteria, toxic, biotic factors, abiotic factors, interactions, allelopathy
Online: 11 May 2021 (10:36:33 CEST)
Environmental genetics-related modern methods are shown as important indicators of various cyanotoxins syntheses, and their knowledge and use are critically analyzed. Microcystins and other cyanotoxins loads and syntheses are related to different drivers, like various chemical elements and compounds (especially nutrients, such as nitrogen and phosphorus, and their ratio), then to the light, conductivity, temperature, and other climatical and hydrological factors, to which spatial and geographical features (such as the surface of the water bodies) have to be added. The biotic relationships include different specific and supraspecific, uni- and bilateral links between the cyanobacteria, and subsequently their synthesized toxins, and protozoans (or protoctists), chromists, macrophytes, different systematical and ecological groups of zooplankton, and others. The importance of, but also the gaps in, the knowledge and the scarcity of studies involving ectocrines mediated interactions between different groups of algae and plants are highlighted. The paper ends with an interesting classification of lakes' trophicity, illustrated with conceptual diagrams, based on possible scenarios of cyanobacteria behavior.
ARTICLE | doi:10.20944/preprints202011.0611.v1
Subject: Life Sciences, Biochemistry Keywords: cyanobacteria; thermal mud; natural products; anti-inflammatory; bioactivity
Online: 24 November 2020 (10:53:33 CET)
Background: The Balaruc-les-Bains’ thermal mud was found to be colonized predominantly by microorganisms, with cyanobacteria constituting the primary organism in the microbial biofilm observed on the mud surface. The success of cyanobacteria in colonizing this specific ecological niche can be explained in part by their taxa-specific adaptation capacities, and also the diversity of bioactive natural products that they synthesize. This array of components has physiological and ecological properties that may be exploited for various applications.
ARTICLE | doi:10.20944/preprints202011.0374.v1
Subject: Life Sciences, Biochemistry Keywords: Biodiversity; Cyanobacteria; Oscillatoriaceae; Nostocaceae; Microcystaceae; fresh water ponds
Online: 13 November 2020 (12:33:54 CET)
Cyanobacterial species (blue-green algae) constitute the major part of the phytoplanktonic biomass during the summer in freshwater ponds. The aim of the research work was to study the biodiversity of cyanobacteria among 20 different freshwater ponds of the Pudukkottai district of Tamil Nadu, India. The morphological identification of cyanobacterial species was carried out using a trinocular microscope. The results showed that the maximum number of cyanobacterial species belonged to Oscillatoriaceae, Nostocaceae, Microcystaceae, Scenedesmaceae, and Desmidiaceae families. Among 25 different families of Cyanobacteria about 42 distinct species were identified. These results showed that the freshwater ponds of the Pudukkottai district have an abundance of cyanobacteria species.
ARTICLE | doi:10.20944/preprints201804.0316.v1
Subject: Engineering, General Engineering Keywords: phosphorus; N:P ratio; cyanobacteria; Planktothrix agardhii; Lake Vombsjön
Online: 24 April 2018 (10:12:39 CEST)
Control of nutrients, mainly nitrogen (N) and phosphorus (P), plays a significant role in preventing cyanobacterial blooms (harmful algal blooms (HABs)). This study aimed at evaluating changes in the risk of the occurrence of cyanobacterial blooms and advancing the understanding of how N and P affect the growth of cyanobacteria in a eutrophic lake, Lake Vombsjön, in southern Sweden. Statistical analysis was used to demonstrate the pattern of cyanobacterial blooms, that the highest content present in September and the later that algal blooms occur, the more likely it is a cyanobacterial bloom as cyanobacteria became dominating in October and November (90%). Two hypothesises tested in Lake Vombsjön confirmed namely that a high total phosphorus (TP) level correlates with an abundance of cyanobacteria and that low N:P ratio (total nitrogen/total phosphorus < 20) favours the growth of cyanobacteria. To control the growth of cyanobacteria in Lake Vombsjön, the TP level should be kept below 20 µg/L and the N:P ratio be maintained at a level of over 20. The two species Planktothrix agardhii, and Pseudanabaena spp. should be carefully monitored especially in late autumn. Future work should consider any high degree of leakage from the sediment of the dissolved phosphorus available there.
ARTICLE | doi:10.20944/preprints202111.0141.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: salinity, light, growth, microalgae, Amphidinium, Nephroselmis, Tetraselmis, Asteromonas, Dunaliella
Online: 8 November 2021 (13:20:55 CET)
After a 1.5 year screening survey in the lagoons of Western Greece in order to isolate and culture sturdy species of microalgae for aquaculture or other value added uses, as dictated primarily by a satisfactory potential for their mass-culture, five species emerged and their growth was monitored in laboratory conditions. Amphidinium carterae, Nephroselmis sp., Tetraselmis sp. (var. red pappas), Asteromonas gracilis and Dunaliella sp. were batch cultured using low (20 ppt), sea (40 ppt) and high salinity (50 or 60 or 100 ppt) and in combination with a low (2000 lux) and high (8000 lux) intensity of illumination. The results exhibited that all these species can be grown adequately in all salinities and with best growth in terms of maximum cell density, specific growth rate (SGR) and biomass yield (g dry weight/L) at high illumination (8000 lux). The five species examined exhibited different responses in the salinities used, Amphidinium clearly does best in 20 ppt far better than 40 ppt and even more than 50 ppt. Nephroselmis and Tetraselmis grow almost the same in 20 and 40 ppt and less well in 60 ppt. Asteromonas does best in 100 ppt although it can grow quite well in both 40 and 60 ppt. Dunaliella grows equally well in all salinities (20-40-60 ppt). Concerning productivity as maximum biomass yield at the end of the culture period, first rank is occupied by Nephroselmis with ~3.0 g d.w./L, followed by Tetraselmis (2.0 g/L), Dunaliella (1.58 g/L), Amphidinium (1.19 g/L) and Asteromonas (0.7 g/L) with all values recorded at high light (8000 lux).
ARTICLE | doi:10.20944/preprints202007.0176.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: dewatering; response surface methodology; Arduino; aluminum electrodes; microalgae harvesting
Online: 9 July 2020 (07:46:18 CEST)
Microalgal harvesting is one of the most challenging processes in the development of algal research and development. Several methods, such as centrifugation, flocculation, and filtration, are available at the laboratory scale. However, the requirement of expensive pieces of equipment and the possibility of biomass contamination are recurring gaps that hinder the development of microalgae I+D in different parts of the world. Recently, the electroflotation has been proved as a suitable method for the harvesting of different species of microalgae and cyanobacteria. To this day, there are no companies that sell laboratory-scale electroflotation equipment; this is mainly due to the gap in the knowledge on which factors (time, mixing rate, number of electrodes, and others) will affect the efficiency of concentration without reducing the biomass quality. This paper aims to build an innovative low-cost electroflotation system under 300 USD with cheap and resistant materials. To achieve our goal, we test the interaction of three variables (time, mixing rate, and amount of electrodes) were evaluated. Results showed that an efficiency closer to 100% could be achieved under 20 minutes using >10 electrodes and 150 rpm. We hope this innovative approach can be used by different researchers to improve our knowledge of the concentration and harvesting of algae and cyanobacteria.
ARTICLE | doi:10.20944/preprints201909.0021.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Microalgae; hydrothermal liquefaction; pretreatment, low O and N biocrude
Online: 2 September 2019 (10:33:06 CEST)
A hydrothermal pretreatment of the microalga Nannochloropsis gaditana at mild temperatures has been studied in order to reduce N and O content in the biocrude obtained by hydrothermal liquefaction (HTL). The work is focused on the evaluation of temperature, reactor loading and time (factors) to maximize the yield of the pretreated biomass and the heteroatom contents transferred from the microalga biomass to the aqueous phase (responses). The study followed the factorial design and response surface methodology. An equation for every response has been obtained, which leads to the accurate calculation of the operating conditions required to obtain a given value of these responses. Temperature and time are critical factors with a negative effect on the pretreated biomass yield, but a positive one on the N and O recovery in the aqueous phase. The slurry concentration has to be low to increase heteroatom recovery and high to maximize the pretreated microalga yields
ARTICLE | doi:10.20944/preprints202211.0199.v1
Subject: Biology, Plant Sciences Keywords: cyanobacteria; photosystem; fast fluorescence kinetics; optical microcavity; fluorescence microscopy
Online: 10 November 2022 (11:05:24 CET)
Photosynthesis is one the most important biological processes on earth, producing life-giving oxygen and is the basis for a large variety of plant products. Measurable properties of photosynthesis provide information about its biophysical state and, in turn, the physiological conditions of a photoautotrophic organism. For instance, chlorophyll fluorescence of an intact photosystem is not linear as in the case of a single fluorescent dye in solution, but shows temporal changes related to the quantum yield of the photosystem. Commercial photosystem analyzers already use the fluorescence kinetics characteristics of photosystems to infer the viability of organisms under investigation. Here, we provide a novel approach based on an optical Fabry-Pérot microcavity or that enables the readout of photosynthetic properties and activity for an individual cyanobacterium. This approach offers a completely new dimension of information, which would normally be lost due to averaging in ensemble measurements obtained from a large population of bacteria.
ARTICLE | doi:10.20944/preprints202206.0298.v1
Subject: Biology, Ecology Keywords: cyanosphere; cyanobacteria; Cyanocohniella; Llayta; macrocolonies; metagenomic-assembled genome; microbiome
Online: 21 June 2022 (16:11:44 CEST)
Cyanobacterial macrocolonies known as Llayta are found at Andean wetlands and consumed since pre-Columbian times in South America. Macrocolonies of filamentous cyanobacteria are niches for colonization by other microorganisms; however, the microbiome of edible Llayta has not been explored. Based on a culture-independent approach, we report the presence, identification and metagenomic genome reconstruction of Cyanocohniella sp. LLY associated to Llayta trichomes. The assembled genome of strain LLY is now available for further inquiries, and may be instrumental for taxonomic advances on this genus. All known members of the Cyanocohniella genus have been isolated from salty European habitats. A biogeographic gap for the Cyanocohniella genus is partially filled by the existence of strain LLY at Andes Mountains wetlands in South America as a new habitat. This is the first genome available for members of this genus. Genes involved in primary and secondary metabolism are described providing new insights on the putative metabolic capabilities of Cyanocohniella sp. LLY. The reconstructed genome of strain LLY is now available and instrumental for further inquiries and taxonomic advances on the genus Cyanocohniella.
REVIEW | doi:10.20944/preprints202103.0212.v1
Subject: Biology, Anatomy & Morphology Keywords: Cyanobacteria; Arthrospira; species concept; typus; species concept in prokaryotes
Online: 8 March 2021 (11:18:31 CET)
Cyanobacteria are prokaryotes whose taxonomy follows the same rules of a code (the International Botanical Nomenclature Code, IBNC) built for eukaryotic photosynthetic organisms. Hence, names of cyanobacteria follow the same rules and are assigned to biological entities (species) that should correspond to eukaryotic species. The main difficulty in the current situation is that the species concept in eukaryotes is based theoretically mainly on the biological species concept, that is centered on genetic exchange through sexual reproduction or lack of them. However, as shown, this difference is important from a theoretical point of view, but also in eukaryotes, the boundaries between different species are very rarely checked experimentally by direct observation of sexual barriers and hybridization events. The main concept for species delimitation is hence that related to morphology and, more recently and always in relation to morphology, DNA sequences. The introduction of distances obtained from matrixes of aligned sequences in the framework of a barcoding project provides a quantitative interpretation of species delimitation in relation to genetic distance that can be used both in eukaryotes and prokaryotes. However, the introduction of quantitative criteria needs the definition of distance thresholds to identify the boundaries between different species and, for doing that, it is necessary to test the distance thresholds in models of traditionally defined and recognized species. An alternative approach may be the comparison of the molecular distance (quantitative approach) to data about the capability of strains/species to exchange genetic information. Unfortunately data about this last question is still scarce. The adoption of molecular criteria to check species boundaries based on morphological characters has proved particularly challenging in cyanobacteria: a known example is provided. In conclusion, the only possible approach appears to be the association of molecular data to the increase of available data about the cell structure and the variation thereof in different physiological situations, particularly at the ultrastructural level. A further necessity is the check of the typus for a large number of cyanobacteria species, often based on old basionyms. In many of these cases the typus is often a drawing and more rarely a herbarium specimen or a microscope slide. In many cases an epitypification or a neotypification appears to be necessary.
ARTICLE | doi:10.20944/preprints201905.0319.v1
Subject: Life Sciences, Microbiology Keywords: cyanobacteria; protease inhibitors; digestive enzyme; daphnia; HPLC; UV/Vis
Online: 27 May 2019 (12:56:49 CEST)
Cyanobacterial mass developments in eutrophic ponds and lakes are a major concern for lake management, as many cyanobacteria produce a huge variety of toxic secondary metabolites, e.g. microcystins. The aim of this research was to culture a strain of the cyanobacterium Microcystis sp strain BM25, to observe its biomass production and to isolate and purify protease inhibitors from this cyanobacterial biomass. Different secondary metabolites were isolated following a standard bioassay-guideline. Isolation was performed, with an enzymatic protease assay as bioassay. High performance liquid chromatography was used to identify different fractions of secondary metabolite from the strain BM25. Moreover, protease homogenates were isolated from Daphnia magna in order to test the inhibitors against naturally occurring major digestive proteases trypsin and chymotrypsin. It was measured that 60% MeOH and the 80% MeOH C18-SPE fraction inhibits chymotrypsin activity 98% (6 nmol pNA min-1 mg-1) and 99 % (4 nmol pNA min-1 mg-1), respectively. In contrast, trypsin activity was not inhibited by methanolic extracts of this cyanobacterium strain.
ARTICLE | doi:10.20944/preprints201904.0192.v1
Subject: Life Sciences, Microbiology Keywords: cyanobacteria; natural products; metabolites; biological activities; producers; chemical classes
Online: 17 April 2019 (06:05:45 CEST)
Cyanobacteria are photosynthetic microorganisms that colonize diverse environments worldwide, ranging from ocean to freshwaters, soils, and extreme environments. Their adaptation capacities and the diversity of natural products (molecules, metabolites, or compounds) that they synthesize support the cyanobacterial success for the colonization of their respective ecological niches. Although cyanobacteria are well-known for their toxin production and their relative deleterious consequences, they also produce a large variety of molecules that exhibit beneficial properties with high potential for various fields of application (e.g., synthetic analog of the dolastatin 10 used against Hodgkin lymphoma). The present review specially focuses on the beneficial activities of cyanobacterial molecules described so far. Based on an analysis of 670 papers, it appears that more than 90 genera of cyanobacteria have been found to produce compounds with potential beneficial activities, most of them belonging to the orders Oscillatoriales, Nostocales Chroococcales, and Synechococcales. The rest of the cyanobacterial orders (i.e., Pleurocapsales, Chroococcidiopsales, and Gloeobacterales) remain poorly explored in terms of their molecular diversity and relative bioactivity. The diverse cyanobacterial molecules presenting beneficial bioactivities belong to 10 different chemical classes (alkaloids, depsipeptides, lipopeptides, macrolides/lactones, peptides, terpenes, polysaccharides, lipids, polyketides, and others) that exhibit 14 major kinds of bioactivity. However, no direct relation between the chemical class and the bioactivity of these molecules has been demonstrated. We further selected and specifically described 50 molecule families according to their specific bioactivities and their potential uses in pharmacology, cosmetology, agriculture, or other specific fields of interest. This up-to-date review takes advantage of the recent progresses in genome sequencing and biosynthetic pathway elucidation, and presents new perspectives for the rational discovery of new cyanobacterial metabolites with beneficial bioactivity.
REVIEW | doi:10.20944/preprints202301.0361.v1
Subject: Biology, Other Keywords: Biomass valorization; Microalgae; Nutrient recovery; Purple phototrophic bacteria; Swine manure
Online: 19 January 2023 (12:20:24 CET)
Piggery wastewater (PWW) is characterized by its high concentrations of organic matter and ammonium, and by their odour nuisance. Traditionally, PWW has been treated in open anaerobic lagoons, anaerobic digesters and activated sludge systems, which exhibit high greenhouse gas emissions, a limited nutrients removal and a high energy consumption, respectively. Photosyn-thetic microorganisms can support a sustainable PWW treatment in engineered photobioreactors at low operating costs and with an efficient recovery of carbon, nitrogen and phosphorous. These microorganisms are capable of absorbing solar irradiation through the photosynthesis process to obtain energy, which is used for their growth and associated carbon and nutrients assimilation. Purple phototrophic bacteria (PPB) represent the photosynthetic microorganisms with the most versatile metabolism in nature, while microalgae are the most studied photosynthetic microor-ganisms in recent years. This review describes the fundamentals, symmetry and asymmetry of PWW treatment using photosynthetic microorganisms such as PPB and microalgae. The main photobioreactor configurations along with the potential of PPB and microalgae biomass valori-zation strategies are also discussed.
ARTICLE | doi:10.20944/preprints202201.0211.v1
Subject: Biology, Plant Sciences Keywords: microalgae; CRISPR/Cas9; gene editing; spermidine; SPD1; auxotrophy; selectable marker
Online: 14 January 2022 (11:55:22 CET)
Biotechnological application of the green microalga Chlamydomonas reinhardtii hinges on the availability of selectable markers for effective expression of multiple transgenes. However, biological safety concerns limit the establishment of new antibiotic resistance genes and until today, only few auxotrophic markers exist for C. reinhardtii. The recent improvements in gene editing via CRISPR/Cas9 allows directed exploration of new endogenous selectable markers. Since editing frequencies with CRISPR/Cas9 techniques are often low, the Cas9-sgRNA ribonucleoprotein (RNP) delivery protocol was strategically optimized by applying nitrogen starvation to the pre-culture, increasing editing frequencies from 10% to 66% after pre-selection. Probing the essential polyamine biosynthesis pathway, the spermidine synthase gene (SPD1) is shown to be a potent selectable marker with versatile biotechnological applicability. Very low levels of spermidine (0.75 mg/L) were required to maintain normal mixotrophic and phototrophic growth in newly designed spermidine auxotrophic strains. Complementation of these strains with a synthetic SPD1 gene was achieved when the mature protein was targeted to either the cytosol or the chloroplast. This work highlights the potential of new selectable markers for biotechnology as well as basic research and proposes an effective pipeline for the identification of new auxotrophies in C. reinhardtii.
COMMUNICATION | doi:10.20944/preprints202106.0616.v1
Subject: Biology, Anatomy & Morphology Keywords: olive-oil mill wastewater; wastewater; microalgae; Chlorella sp.; phenolic compounds
Online: 25 June 2021 (11:42:54 CEST)
The Mediterranean diet has among its cornerstones the use of olive oil for its nutraceutical and organoleptic properties. Despite the numerous merits, olive-oil mill wastewater (OMWW), which is generated by the olive-oil extraction process, is one of the most serious environmental pollutants in the Mediterranean countries. The polluting potential of OMWW is due to its high content of tannins, polyphenols, polyalcohols, pectins and lipids. In this experiment, we tested the ability of five microalgae of the Chlorella group (SEC_LI_ChL_1, CL-Sc, CL-Ch, FB and Idr) in lowering the percentage of total phenolic compounds in vegetation water. In order to close the recovery cycle of a fortified citrus olive oils previously developed, we tested the vegetation wa-ter obtained with three different extraction processes (conventional, lemon and orange peels) at three concentrations each (10%, 25% and 50%). Results showed that strains Idr, FB and CL-Sc from the Lake Massaciuccoli can tolerate vegetation water from conventional and lemon peels extraction up to 25%; these strains can also reduce the phenolic compounds within the tests. The results demonstrate that the application of microalgae for OMWW treatment represent an inter-esting opportunity, and an eco-friendly low-cost solution to be developed within the companies as a full-scale approach.
REVIEW | doi:10.20944/preprints202105.0572.v1
Subject: Biology, Other Keywords: microalgae; marine bacteria; quorum sensing signals; alkyl quinolones; microbial loop
Online: 24 May 2021 (13:34:11 CEST)
Quorum sensing (QS) describes a process by which bacteria can sense the local cell density of their own species, thus enabling them to coordinate gene expression and physiological processes on a community-wide scale. Small molecules called autoinducers or QS signals, which act as intraspecies signals, mediate quorum sensing. As our knowledge of QS has progressed, so too has our understanding of the structural diversity of QS signals, along with the diversity of bacteria conducting QS and the range of ecosystems in which QS takes place. It is now also clear that QS signals are more than just intraspecies signals. QS signals mediate interactions between species of prokaryotes, and between prokaryotes and eukaryotes. In recent years, our understanding of QS signals as mediators of algae–bacteria interactions has advanced such that we are beginning to develop a mechanistic understanding of their effects. This review will summarize the recent efforts to understand how different classes of QS signals contribute to the interactions between planktonic microalgae and bacteria in our oceans, primarily N-acyl-homoserine lactones, their degradation products tetramic acids, and 2-alkyl-4-quinolones. In particular, this review will discuss the ways in which QS signals alter microalgae growth and metabolism, namely as direct effectors of photosynthesis, regulators of the cell cycle, and as modulators of other algicidal mechanisms. Furthermore, the contribution of QS signals to nutrient acquisition is discussed, and finally how microalgae can modulate these small molecules to dampen their effects.
REVIEW | doi:10.20944/preprints202008.0469.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: microalgae; thermochemical processing; biofuel and bioenergy; torrefaction; liquefaction; pyrolysis; gasification
Online: 21 August 2020 (04:24:54 CEST)
Over the last decades, microalgal biomass has gained a significant role in the development of different high-end (nutraceuticals, colorants, food supplements, and pharmaceuticals) and low-end products (biodiesel, bioethanol, and biogas) due to rapid growth and high carbon fixing efficiency. Therefore, microalgae are considered a useful and sustainable resource to attain energy security while reducing our current reliance on fossil fuels. From the technologies available for obtaining biofuels using microalgae biomass, thermochemical processes (pyrolysis, HTL, gasification) have proven to be processed with higher viability, because they use all biomass. However, the biocrudes obtained from direct thermochemical conversion have substantial quantities of heteroatoms (oxygen, nitrogen, and sulfur) due to the complexity of the biomass's content of chemical components (lipids, carbohydrates, and proteins). As a solution, catalyst-based processes have emerged as a sustainable solution for the increase in biocrude production. This paper's objective is to present a comprehensive review of recent developments on catalyst mediated conversion of algal biomass. Special attention will be given to operating conditions, strains evaluated, and challenges for the optimal yield of algal-based biofuels through pyrolysis and HTL.
ARTICLE | doi:10.20944/preprints202002.0168.v1
Subject: Materials Science, Nanotechnology Keywords: Carbon nanotubes; Microalgae; Mode of action; Nanofibers; Silica nanotubes; Toxicity
Online: 13 February 2020 (12:33:37 CET)
Nanoparticles (NPs) have various applications in medicine, cosmetics, optics, catalysis, environmental purification, and other areas nowadays. With an increasing annual production of NPs, the risks of their harmful influence to the environment and human health is rising. Currently, our knowledge about the mechanisms of interaction between NPs and living organisms is limited. Additionally, poor understanding of how physical and chemical characteristic and different conditions influence the toxicity of NPs restrict our attempts to develop the standards and regulations which might allow us to maintain the safe living conditions. The marine species and their habitat environment are under continuous stress due to anthropogenic activities which result in the appearance of NPs in the aquatic environment. Our study aimed to evaluate and compare biochemical effects caused by the influence of different types of carbon nanotubes, carbon nanofibers, and silica nanotubes on four marine microalgae species. We have evaluated the changes in growth-rate, esterase activity, membrane polarization, and size changes of microalgae cells using flow cytometry method. Our results demonstrated that toxic effects caused by the carbon nanotubes strongly correlated with the content of heavy metal impurities in the NPs. More hydrophobic carbon NPs with less ordered structure had a higher impact on the red microalgae P. purpureum because of higher adherence between the particles and mucous covering of the algae; silica NPs caused significant inhibition of microalgae growth-rate predominantly produced by mechanical influence.
REVIEW | doi:10.20944/preprints202012.0696.v1
Subject: Medicine & Pharmacology, Allergology Keywords: microalgae; carotenoids; chlorophylls; lipids; mycosporin-like amino acids; antioxidants; UV-screen
Online: 28 December 2020 (12:15:07 CET)
A prominent feature of stress-tolerant microalgae is their versatile metabolism allowing then to synthesize a broad spectrum of molecules with beneficial effects on many aspects of human body functioning. This is in line with the current understanding that many stress-induced deleterious processes in the human body and in photosynthetic cell are mediated by the same mechanisms such as free-radical attacks and lipid peroxidation. These related risks are kept at bay by optical screening of harmful UV, enzymatic ROS elimination systems, and potent low-molecular antioxidants. Microalgae synthesize a broad spectrum of compounds exerting antioxidant and/or UV-absorbing properties. In microalgae, they increase stress-resilience of these organisms. In human body, they exhibit photoprotective, antiaging, and sunscreen activities. Therefore, these algal metabolites were recognized as promising ingredients for innovative cosmetics and cosmeceutical formulations. Ever increasing effort is being invested into the search for new natural biologically active substances from microalgae. This trend is also fueled by the growing demand for natural raw materials for food, pharmaceuticals and cosmetology associated with the global transition to a "greener" lifestyle. Here, we review the currently accumulated knowledge about the main groups of cosmeceutical compounds from microalgae.
ARTICLE | doi:10.20944/preprints202108.0484.v1
Subject: Biology, Other Keywords: cyanobacteria; metabolomics; high-resolution mass spectrometry; secondary metabolite induction; culture conditions
Online: 25 August 2021 (10:48:20 CEST)
Cyanobacteria are microorganisms able to adapt to a wide variety of environmental conditions and abiotic stresses. They produce a very large number of metabolites that can participate in the adaptation of cyanobacteria to a large range of resources such as light, temperature, or nutrient. The metabolites variation is one way to understand the physiological status and adaptation of cells. In this study, we aim to understand how the diversity and the dynamics of the whole metabolome is dependent of the growth phases and under control of abiotic factors (e.g. light intensity and temperature). The cyanobacteria Aliinostoc sp. PMC 882.14 was selected for its large number of biosynthetic gene clusters. Metabolomes were analyzed by using mass spectrometry (qTOF-MS/MS) combined with untargeted analysis to investigate the metabolite dynamics. Significant variations were characterized between exponential and stationary phases, whatever the culture conditions (“control”, “higher light”, or “higher temperature”). ”Higher light” and “higher temperature” favored the synthesis of metabolites belonging to the same molecular families. Among highly regulated metabolites, we observe the presence of mycosporine-like amino acids (MAAs), and various variants of somamides, microginins, and microviridins. Through Aliinostoc sp. PMC 882.14, this study shows the importance of knowing the physiological state of cyanobacteria for comparative global metabolomics and questions the regulation processes involve into metabolite families production. Our results also open up new perspectives in the context of the production of targeted bioactive metabolites.
ARTICLE | doi:10.20944/preprints201805.0169.v1
Subject: Earth Sciences, Environmental Sciences Keywords: cyanobacteria; cyanotoxins; nutrient enrichment; akinetes; harmful algal blooms; PCR; phylogenetic analyses
Online: 10 May 2018 (15:37:51 CEST)
The presence of harmful algal blooms (HABs) and cyanotoxins in drinking water sources poses a great threat to human health. The current study employed molecular techniques to determine the occurrence of non-toxic and toxic cyanobacteria species in the Limpopo River basin based on the phylogenetic analyses of 16S rRNA gene. The bottom sediments samples were collected from selected rivers: Limpopo, Crocodile, Mokolo, Mogalakwena, Nzhelele, Lephalale, Sand Rivers (South Africa); Notwane (Botswana), Shashe River and Mzingwane River (Zimbabwe). The physical-chemical analysis of the bottom sediments showed the availability of nutrients, nitrates and phosphates, in excess of 0.5 mg/l for most of river sediments, alkaline pH and salinity in excess of 500 mg/l. The FlowCam showed the dominant cyanobacteria species identified from the samples were Microcystis species, followed by Cylindrospermopsis raciborskii, Phormidium and Planktothrix species and this was confirmed by molecular techniques. Nevertheless, two samples showed the amplification of cylindrospermopsin polyketide synthetase gene (S3 and S9) while two samples showed amplification for microcystin/nodularin synthetase gene (S8 and S13). Thus these findings may imply the presence of toxic cyanobacteria species in the river sediments. The presence of cyanobacteria may be hazardous to human because rural communities and farmers who abstract water from Limpopo river catchment for human consumption, livestock and wildlife watering and irrigation.
REVIEW | doi:10.3390/sci1020043
Subject: Keywords: airborne wind turbines; climate change; EROI; microalgae; photolysis; renewable energy; technology introduction
Online: 7 August 2019 (00:00:00 CEST)
Because of the near-term risk of extreme weather events and other adverse consequences from climate change, and, at least in the longer term, global fossil fuel depletion, there is world-wide interest in shifting to noncarbon energy sources, especially renewable energy (RE). Because of possible limitations on conventional renewable energy sources, researchers have looked for ways of overcoming these shortcomings by introducing radically new energy technologies. The largest RE source today is bioenergy, while solar energy and wind energy are regarded as having the largest technical potential. This paper reviews the literature on proposed new technologies for each of these three RE sources: microalgae for bioenergy, photolysis and airborne wind turbines. The main finding is that their proponents have underestimated the difficulties facing their introduction on a very large scale.
Subject: Life Sciences, Biochemistry Keywords: Dunaliella salina; microalgae; red LED; blue LED; growth; carotenoids; plastoquinol:oxygen oxidoreductase; photosynthesis
Online: 19 April 2019 (09:47:41 CEST)
The halotolerant photoautotrophic marine microalga Dunaliella salina is one of the richest sources of natural carotenoids. Here we investigated the effects of high intensity blue, red and white light from light emitting diodes (LED) on the production of carotenoids by strains of D. salina under nutrient sufficiency and strict temperature control favouring growth. Growth in high intensity red light was associated with carotenoid accumulation and a high rate of oxygen uptake. On transfer to blue light, a massive drop in carotenoid content was recorded along with very high rates of photo-oxidation. In high intensity blue light, growth was maintained at the same rate as in red or white light, but without carotenoid accumulation; transfer to red light stimulated a small increase in carotenoid content. The data support chlorophyll absorption of red light photons to reduce plastoquinone in photosystem II, coupled to phytoene desaturation by plastoquinol:oxygen oxidoreductase, with oxygen as electron acceptor. Partitioning of electrons between photosynthesis and carotenoid biosynthesis would depend on both red photon flux intensity and phytoene synthase upregulation by the red light photoreceptor, phytochrome. Red light control of carotenoid biosynthesis and accumulation reduces the rate of formation of reactive oxygen species (ROS) as well as increases the pool size of anti-oxidant.
ARTICLE | doi:10.20944/preprints202201.0437.v1
Subject: Biology, Plant Sciences Keywords: cyanobacteria; Phormidium; Cyanothece; culture growth; light; chlorophyll; carotenoids; phycocyanin; phycoerythrin; allophycocyanin; phycobiliproteins
Online: 28 January 2022 (12:21:12 CET)
Cyanobacteria are extensively studied and cultured because they can produce many value-added substances among which are pigments, mainly the phycobiliproteins phycocyanin (PC), phycoerythrin (PE), allophycocyanin (APC) and chlorophyll-a and carotenoids as well. As numerous cyanobacterial species await optimization for maximizing pigment production, we examined here two local marine species, Phormidium sp. and Cyanothece sp. batch cultured under 18-19.5 oC, at 40 ppt salinity with Walne’s nutrient medium, using white LED light of low (2000 lux) and high (8000 lux) intensity and additionally blue, green and red LED light. Significant differences were found among the intensities and colors of light used. Maximum growth was induced by high white light in both species (2.15 g dw/L in Phormidium and 1.47 g/L in Cyanothece). Next to them was green light (1.25 g/L) in Cyanothece and low white and green (1.26 – 1.33 g/L) in Phormidium. Green light maximized phycocyanin content in Phormidium (0.45 mg/mL), while phycoerythrin was maximized (0.17 mg/mL) by blue light and allophycocyanin by all colors (~0.80 mg/mL). All colors maximized phycocyanin in Cyanothece (~0.32 mg/mL) while phycoerythrin and allophycocyanin were maximized under green light (~0.138 and 0.38 mg/mL respectively). In Phormidium maximization of chlorophyll-a (9.3 μg/mL) was induced by green light while total carotenoids and b-carotene (3.05 and 0.89 μg/mL respectively) by high white light. In Cyanothece both white light intensities along with green light maximized chlorophyll-a content (~9 μg/mL) while high white light and green maximized total carotenoids (2.6-3.0 μg/mL).
CONCEPT PAPER | doi:10.20944/preprints202110.0017.v1
Subject: Engineering, Energy & Fuel Technology Keywords: Bioenergy; marine fermentation; seawater; marine yeast; microalgae; seaweed; circular economy; high value chemicals
Online: 1 October 2021 (12:19:47 CEST)
Biofuels have many environmental and practical benefits as a transportation fuel. They are among the best alternatives to fossil fuels due to their capacity for negative carbon emissions, which is vital for archiving the global ambition of a Net-Zero Economy. However, conventional biofuel production takes place on inland sites and relies on freshwater and edible crops (or land suitable for edible crop production), which has led to the food vs fuel debate. It also suffers technical and economical barriers due to the energy balance and the cost of production compared to fossil fuels. Establishing a coastal integrated marine biorefinery (CIMB) system for the simultaneous production of biofuels, high-value chemicals, and other co-products could be the ultimate solution. The proposed system is based on coastal sites and relies on marine resources including seawater, marine biomass (seaweed) and marine microorganisms (marine yeasts and marine microalgae). The system will not require the use of arable land and freshwater in any part of the production chain and will be linked to offshore renewable energy sources to increase its economic and environmental value. This article aims to introduce the CIMB system as a potential vehicle for addressing global warming and speeding the global effort on climate change mitigation as well as increasing global water, food and energy security. I hope this perspective may serve to draw attention into research funding for this approach.
ARTICLE | doi:10.20944/preprints202104.0371.v1
Subject: Engineering, Automotive Engineering Keywords: Dictyosphaerium pulchellum; Freshwater microalgae; Growth kinetics; Heavy metal; Lipid accumulation; Micractinium pusillum; Photosynthesis; Toxicity
Online: 14 April 2021 (12:24:04 CEST)
Heavy metals have adverse effects on microalgae growth and metabolism. Photosynthesis and lipid profile are quite sensitive to heavy metal toxicity. The impact of chromium (Cr) on growth and photosynthetic activity of Dictyosphaerium pulchellum and Micractinium pusillum exposed to different concentrations (0 – 500 μg L-1) was investigated for 11 days. The influence of Cr on cell density and cell number followed similar trends, indicating a possible correlation among these growth responses. A significant (p < 0.05) increase in lipid content was observed with the increasing concentration of Cr however, growth was suppressed at higher concentrations exceeding 100 μg L-1. Addition of Cr in the cell culture medium showed a negative effect on quantum yield (Fv/Fm) and a photosynthetic inhibition of > 65% was noted in both species at 500 μg L-1. However, the lipid gravimetric analysis presented inner cell lipid content up to 36% and 30% of dry weight biomass for D. pulchellum and M. pusillum, respectively. The effects of chromium on growth and lipid accumulation in both microalgae species was concentration and exposure time dependent. This shows that an appropriate concentration of chromium in culture medium could be beneficial for higher lipid accumulation in freshwater eukaryotic microalgae species.
ARTICLE | doi:10.20944/preprints202003.0056.v1
Subject: Life Sciences, Other Keywords: Hermetia illucens prepupae; Black soldier fly; coffee silverskin; microalgae; toxic metals; bioaccumulation; chemical hazard
Online: 4 March 2020 (09:48:16 CET)
Among other species, Black Soldier Fly (Hermetia illucens, HI, Diptera, Stratiomydae) has the great potential as food and feed ingredient in the EU, particularly thanks to its preference for organic waste as growth substrate. The production of insects as livestock feed or as food ingredient requires a strict monitoring of heavy metal content in the growth substrate in order to secure its safe. This study aims to investigate the presence of toxic metals cadmium, lead, mercury, arsenic, and nickel in HI prepupae and their growth substrates based on coffee roasting by-product and microlagae Schizochytrium sp. and Isochrysis sp. Analyses were carried out via graphite furnace atomic absorption spectrophotometry for Cd, Pb, Ni, and As, and via Direct Mercury Analyzer for Hg. All metal concentrations found in growth substrates were below the legal limit of undesirable substances in animal feed (2002/32/EC). Metals concentrations in HI prepupae were in the range (mg kg-1 wet weight): Cd 0.072–0.084, Pb 0.018–0.026, Hg 0.010–0.032, As 0.036–0.047, Ni 0.18–0.76. HI prepupae accumulate Cd, Pb and Hg, but our results indicate that the risk of exposure to metals from consumption of HI prepupae is relatively low and in compliance with European Union regulations.
ARTICLE | doi:10.20944/preprints202011.0659.v1
Subject: Biology, Anatomy & Morphology Keywords: bioactive compounds; cyanobacteria; cytoskeleton; F-actin; microcystins; microtubules; Oryza sativa; oxidative stress; plant cell
Online: 26 November 2020 (09:52:01 CET)
Microcystins (MCs) are cyanobacterial toxins and potent inhibitors of protein phosphatases 1 (PP1) and 2A (PP2A), which are involved in plant cytoskeleton (microtubules and F-actin) organization. Therefore, studies on the toxicity of cyanobacterial products on plant cells have so far being focused on MCs. In this study, we investigated the effects of extracts from 16 (4 MC-producing and 12 non-MC-producing) cyanobacterial strains from several habitats, on various enzymes (PP1, trypsin, elastase), on the plant cytoskeleton and H2O2 levels in Oryza sativa (rice) root cells. Seedling roots were treated for various time periods (1, 12 and 24h) with aqueous cyanobacterial extracts and underwent either immunostaining for α-tubulin or staining of F-actin with fluorescent phalloidin. DCF-DA staining was performed for H2O2 imaging. The enzyme assays confirmed the bioactivity of the extracts of not only MC-rich (MC+), but also MC-devoid (MC-) extracts, which induced major time-dependent alterations on both components of the plant cytoskeleton. These findings suggest that a broad spectrum of bioactive cyanobacterial compounds, apart from MCs or other known cyanotoxins (such as cylindrospermopsin), can affect plants by disrupting the cytoskeleton.
ARTICLE | doi:10.20944/preprints202206.0244.v1
Subject: Earth Sciences, Environmental Sciences Keywords: contaminants of emerging concern; bisphenol; microalgae; Phaeodactylum tricornutum; bacteria, extracellular vesicles; electron microscopy; flow cytometry; mass spectrometry
Online: 17 June 2022 (03:57:22 CEST)
Small cellular particles are released into the surroundings of cells and are proposed to play an important role in intercellular communication and consequently the responses of microbial com-munities to environmental stressors. We studied the connection between the small cellular parti-cles and the efficiency of three culture series of the microalge Phaeodactylum tricornutum and bac-teria (axenic microalgae, bacterial culture and co-culture of the two) in removing bisphenols from their growth medium. The microorganism growth rate was determined by flow cytometry, protein profiles were examined by protein gel electrophoresis, cultures and small cellular particle isolates were imaged by scanning electron microscopy, and bisphenols were analyzed using gas chroma-tography coupled with tandem mass spectrometry (GC-MS/MS). Higher growth rates of microal-gae were observed in the co-culture than in the axenic microalgal culture, while the presence of bisphenols neither influenced the morphology of the microalgal cells, protein profiles, nor the small cellular particle isolates. Biotic removal of bisphenols ranged from 0% to 71% and differed among the culture series in a compound-specific manner. However, it remains unclear which mechanisms influenced algal growth and bisphenol removal. Further research on the mechanisms of interspecies communication is needed to advance our understanding of microbial communities at the nano-level.
REVIEW | doi:10.20944/preprints202102.0088.v1
Subject: Biology, Anatomy & Morphology Keywords: Microbiome; sound exposure; noise pollution; microalgae; artificial light; bioacoustics; ecosystem health; light pollution; photo-sonic restoration hypothesis
Online: 2 February 2021 (13:12:10 CET)
Globally, anthropogenic sound and artificial light pollution have increased to alarming levels. Evidence suggests that these can disrupt critical processes that impact ecosystems and human health. However, limited focus has been given to the potential effects of sound and artificial light pollution on microbiomes. Microbial communities are the foundations of our ecosystems. They are essential for human health and provide myriad ecosystem services. Therefore, disruption to microbiomes by anthropogenic sound and artificial light could have important ecological and human health implications. In this mini-review, we provide a critical appraisal of available scientific literature on the effects of anthropogenic sound and light exposure on microorganisms and discuss the potential ecological and human health implications. Our mini-review shows that a limited number of studies have been carried out to investigate the effects of anthropogenic sound and light pollution on microbiomes. However, based on these studies, it is evident that anthropogenic sound and light pollution have the potential to significantly influence ecosystems and human health via microbial interactions. Many of the studies suffered from modest sample sizes, suboptimal experiments designs, and some of the bioinformatics approaches used are now outdated. These factors should be improved in future studies. This is an emerging and severely underexplored area of research that could have important implications for global ecosystems and public health. Finally, we also propose the photo-sonic restoration hypothesis: does restoring natural levels of light and sound help to restore microbiomes and ecosystem stability?
ARTICLE | doi:10.20944/preprints201905.0204.v2
Subject: Engineering, Civil Engineering Keywords: groundwater; pre-treatment; contact filtration; infiltration ponds; nutrients removal; TP; Cyanobacteria; Cyanotoxin; microcystin-LR; eutrophic lakes; TOC
Online: 19 August 2019 (04:08:58 CEST)
Artificial groundwater recharge is commonly used for drinking water supply. The resulting water quality is highly dependent on the raw water quality. In many cases, pre-treatment is required. Pre-treatment improves the drinking water quality, although how and to what extent it affects the subsequent pond water quality and infiltration process, is still unknown. We evaluated two treatment systems by applying different pre-treatment methods for raw water from a eutrophic and temperate lake. An artificial recharge pond was divided into two parts, where one received raw water, only filtered through a micro-screen with 500 µm pores (control treatment), while the other part received pre-treated lake water using chemical flocculation with polyaluminium chloride (PACl) combined with sand filtration, i.e. continuous contact filtration (contact filter treatment). Water quality such as cyanobacterial biomass, microcystin-LR as well as organic matter and nutrients were measured in both treatment processes. We found cyanobacterial biomass and microcystin-LR level after the contact filter treatment was significantly different from the control treatment and also significantly different in the pond water. In addition, with contact filter treatment, total phosphorus (TP) and organic matter removal were significantly improved in the end water, TP was reduced by 96 % (< 20 µg/L) and the total organic carbon (TOC) was reduced by 66 % instead of 55 % (TOC content around 2.1 mg/L instead of 3.0 mg/L). This full-scale onsite experiment demonstrated effective pre-treatment would benefit a more stable water quality system, with less variance and lower cyanotoxin risk. In a broader drinking water management perspective, the presented method is promising to reduce cyanotoxin risk, as well as TP and TOC, which are all predicted to increase with global warming and extreme weather.
ARTICLE | doi:10.20944/preprints202012.0193.v1
Subject: Keywords: Hemocytes; innate immune cells; Phagocytic Activity; Respiratory Burst; microalgae; immunomodulator; shrimps L. vannamei; Vibrio harveyi; Extracellular Polysaccharide (EPS)
Online: 8 December 2020 (09:57:25 CET)
White shrimps are susceptible to outbreaks of vibriosis because they do not have any adaptive immune system, they only have a non-specific innate immune system. The administration of EPS from microalgae Porphyridium cruentum (synonym: P. purpureum) on shrimps Litopenaeus vannamei was investigated to determine the effect of this immunostimulant on their non specific immune response and to test if EPS can be used as a protective agent for shrimp related to Vibrio infection. EPS was given to shrimps by immersion method on day 1 and booster on day 8. Shrimp hemocytes were taken on day 1 (EPS administration), day 7 (no treatment), day 8 (EPS booster) and day 9 (Vibrio infection) and tested for their immune response on each treatment. Result shows an increase in values of all immune parameters in line with the increasing EPS concentration, except the Differential Haemocyte Count (DHC). In detail, an increase was noted in total hemocytes (THC) value, Phagocytotic Activity (PA), Respiratory Burst (RB) in line as the EPS concentration increase. Although there is a decrease after the infection, the value obtained is not lower than the control value. These results indicate that EPS from Porphyrydium enhances immune parameters in shrimp rapidly and has the ability as an immunostimulant or an immunomodulator. It is a good modulator for the non specific immune cells of Pacific white shrimps, and it can be used as a preventive agent against Vibrio.
ARTICLE | doi:10.20944/preprints202008.0282.v1
Subject: Chemistry, Analytical Chemistry Keywords: cyanobacteria; cyanopeptides; eutrophication; harmful bloom; liquid chromatography tandem mass spectrometry; Global Natural Product Social networking (GNPS); Dereplication strategy.
Online: 12 August 2020 (10:15:46 CEST)
Man-made shallow fishponds in the Czech Republic have been facing a high eutrophication since 1950s. Anthropogenic eutrophication and feeding of fish have strongly affected the physico-chemical properties of water and its aquatic community composition leading to harmful algal bloom formation. In our current study, we have characterised the phytoplankton community across three hypertrophic ponds to assess the phytoplankton dynamics during the vegetation season. We microscopically identified and quantified 29 cyanobacterial taxa comprised of non-toxigenic and toxigenic species. Further, a detailed cyanopeptides (CNPs) profiling was performed using molecular networking analysis of liquid chromatography tandem mass spectrometry (LC–MS/MS) data coupled with dereplication strategy. This MS networking approach coupled with dereplication on online global natural product social networking (GNPS) web platform led us to putatively identify forty CNPs: fourteen anabaenopeptins, ten microcystins, five cyanopeptolins, six microginins, two cyanobactins, a dipeptide radiosumin, a cyclooctapeptide planktocyclin and epidolastatin12. We have applied the binary logistic regression to estimate the CNPs producer by correlating the GNPS data with the species abundance. Usage of The combination of molecular networking and dereplication on online global natural product social networking (GNPS) web platform has proved as a valuable approach for rapid and simultaneous detection of high number of peptides, and rapidly assessing the risk for harmful bloom.
ARTICLE | doi:10.20944/preprints202102.0422.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Hemocytes; Innate Immune Cells; Phagocytic Activity; Respiratory Burst; White-Shrimp; Microalgae; Immunomodulator; Toxicity; Extracellular Polysaccharide; Vibrio harveyi; Danio rerio
Online: 18 February 2021 (15:56:44 CET)
Exopolysaccharides or extracellular polysaccharides (EPS, sPS) represent valuable metabolite compound synthesized from red microalgae. It is a non toxic natural agent and can be applied as immunostimulant. Toxicity test of exopolysaccharides from Porphyridium has been done in-vivo using zebrafish (Danio rerio) embryonic model, or the ZET (Zebrafish Embryotoxicity Test). The administration of extracellular polysaccharide or exopolysaccharides (EPS) from microalgae Porphyridium cruentum (synonym: P. purpureum) on shrimps Litopenaeus vannamei was investigated to determine the effect of this immunostimulant on their non specific immune response and to test if this compound can be used as a protective agent for shrimp related to Vibrio infection. For immune response, exopolysaccharides was given to shrimps by immersion method on day 1 and booster on day 8. Shrimp hemocytes were taken on day 1 (EPS administration), day 7 (no treatment), day 8 (EPS booster) and day 9 (Vibrio infection) and tested for their immune response on each treatment. Result shows that the EPS is not toxic as represented by the normal embryonic development and the mortality data. In the Pacific whiteshrimps, it show an increase in values of all immune parameters in line with the increasing EPS concentration, except the Differential Haemocyte Count (DHC). In detail, an increase was noted in total hemocytes (THC) value, Phagocytotic Activity (PA), Respiratory Burst (RB) in line with the EPS concentration increase. These results and other previous studies indicate that EPS from Porphyridium is safe and it enhances immune parameters in shrimp rapidly and has the ability as an immunostimulant or an immunomodulator. It is a good modulator for the non-specific immune cells of Pacific white shrimps, and it can be used as a preventive agent against vibriosis.
REVIEW | doi:10.20944/preprints202301.0357.v1
Subject: Biology, Other Keywords: cyanotoxins; cyanobacteria; harmful algae bloom; neurodegenerative disease; microcystin; BMAA; non-proteogenic amino acids; mistranslation; amyotrophic lateral sclerosis; Alzheimer’s disease
Online: 19 January 2023 (11:46:59 CET)
Cyanobacteria produce a wide range of structurally diverse cyanotoxins and bioactive cyanopeptides in freshwater, marine, and terrestrial ecosystems. The health significance of these metabolites, which include genotoxic- and neurotoxic agents, is confirmed by continued associations between the occurrence of animal and human acute toxic events and, in the long term, by associations between cyanobacteria and neurodegenerative diseases. One of the implicated mechanisms includes a misincorporation of cyanobacterial non-proteogenic amino acids leading to mistranslation and protein misfolding. A better understanding of the interaction between the cyanopeptide metabolism and the nervous system will be crucial to target or to prevent pathogenic response.
REVIEW | doi:10.20944/preprints201703.0148.v1
Subject: Life Sciences, Other Keywords: microcystin; saxitoxin; cylindrospermopsin; anatoxin-a; anatoxin-a(S); cyanobacteria; organic anion transporting polypeptide; phosphatase inhibitor; acetylcholinesterase; neurotoxicity; water quality; eutrophication; drinking water
Online: 20 March 2017 (06:17:48 CET)
Cyanobacteria are ubiquitous phototrophic bacteria that inhabit diverse environments across the planet. They dominate many eutrophic lakes impacted by excess nitrogen (N) and phosphorus (P) forming dense accumulations of biomass known as cyanobacterial harmful algal blooms or cyanoHABs. Their dominance in eutrophic lakes is attributed to a variety of unique adaptations including N and P concentrating mechanisms, N fixation, colony formation that inhibits predation, vertical movement via gas vesicles, and the production of toxic or otherwise bioactive molecules. While some of these molecules have been explored for their medicinal benefits, others are potent toxins harmful to humans, animals, and other wildlife known as cyanotoxins. In humans these cyanotoxins affect various tissues, including the liver, central and peripheral nervous system, kidneys, and reproductive organs among others. They induce acute effects at low doses in the parts-per-billion range and some are tumor promoters linked to chronic diseases such as liver and colorectal cancer. The occurrence of cyanoHABs and cyanotoxins in lakes presents challenges for maintaining safe recreational aquatic environments and the production of potable drinking water. CyanoHABs are a growing problem in the North American (Laurentian) Great Lakes basin. This review summarizes information on the occurrence of cyanoHABs in the Great Lakes, toxicological effects of cyanotoxins, and appropriate numerical limits on cyanotoxins in finished drinking water.
Subject: Life Sciences, Molecular Biology Keywords: protein/rna world; plasma membrane; cytoplasm; virus world; pre-retro virus; emergence of dna; transcription and replication; first cells; hyperthermophiles; luca; bacteria and archaea; anoxygenic bacteria; oxygenic bacteria; global distribution of cyanobacteria
Online: 15 October 2019 (11:18:58 CEST)
The transition from the Peptide/RNA world to the Protein/RNA world in the hydrothermal vent environment was a major event in the history of life. The advent of proteins utterly changed the conditions of emerging life, representing a watershed in its development. During subsequent translation various protein enzymes emerged driving protocells into a more complex and interconnected system. With their astonishing versatility, the protein enzymes catalyzed crucial biochemical reactions within protocells into more complex biomolecules in diverse metabolic pathways, whereas structural proteins provided strength and permeability in the cell membrane. Four major events followed after availability of various kinds of protein molecules during prebiotic synthesis. These are: (1) the modification of the phospholipid membrane into the plasma membrane; (2) the origin of primitive cytoplasm; (3) the beginnings of the virus world; and (4) the advent of DNA. The first innovation mediated by proteins was the improvement of the cell membrane. The phospholipid membrane was initially evolved in a vent environment from the gradual modification of a fatty acid membrane via an intermediate phosphatidate acid by non-enzymatic reactions. The phospholipid is then synthesized from phosphatidate acid by a series of enzymes. To make the phospholipid membrane more permeable, various protein molecules interacted with the cell membrane. Proteins not only stabilized the wall membrane, but also acted as pumps, preventing some molecules from the protocells from crossing the membrane barriers, while permitting other selected molecules and ions to enter and leave the protocell. The second modification led by proteins is the gradual conversion of the interior of the protocell from a water-like medium into a gel-like cytoplasm, which became the storehouse of a wide range of biomolecules including amino acids, proteins, nucleic acids, ribosomes, as well as salt and water. The third innovation utilizing the newly synthesized proteins was the emergence of the ancient virus world. In the milieu of different kinds of mRNAs in the prebiotic soup, jelly-roll capsid genes originated de novo within genomes of nonviral mRNAs by overprinting. These fragile capsid genes were possibly coated by proteins on the mineral substrate for stability and durability, transforming them into ancient viral particles. These protein coats were random and were not encoded by encased genes. Some protocells might have engulfed these viral particles, when the capsid genes utilized the ribosomes of the host to translate into the appropriate capsid proteins. These capsid proteins then coated the viral genes to make new copies of primordial viruses inside the protocell. Since then, viruses became capsid-encoding organisms. These primordial mRNA viruses parasitized RNA-based protocells, manipulating them to make new copies of themselves. This was the beginning of a relentless war between viruses and their protocellular hosts. The next stage in viral evolution was the emergence of a primitive retrovirus (pre-retrovirus) with a new kind of replicative strategy in a sense that it could turn its RNA into DNA using its own reverse transcriptase enzyme. This is the beginning of the Retro world that facilitated the transition from RNA to DNA genomes. The infection of RNA protocells with pre-retroviruses progressively transferred the RNA genome to a viral DNA genome by retro-transcription. The advent of DNA by the pre-retrovirus marks the fourth innovation, when a number of enzymes had already developed and were utilized by pre-retroviruses. With continued infection, DNA viruses slowly transferred not only their core replication enzymes, such as helicase, primase, and DNA polymerase, to RNA protocells, but also to their DNAs as well. Thus, began the DNA world, when DNA replaced RNA as the major genome of the protocells. With the advent of DNA, replication of information was entirely dissociated from its expression. Because DNA is much more stable than mRNA with more storage capacity, it is a superb archive for information systems in the form of base sequences. DNA progressively took over the replicative storage function of mRNA, leaving the latter for protein synthesis. The new protocell with the DNA genome will diversify into large populations of DNA protocells that will outcompete populations of RNA protocells. Genetic information began to flow from DNA to mRNA to protein in a two-step process involving transcription and translation. In the biological stage, DNA replication was central to the binary fission of the first cell, orchestrated by the duplication of genomes and then the division of the parent cell into two identical daughter cells. It was carried out by a set of enzymes that formed a Z-ring at the site of replication. With the onset of binary fission, the population of primitive cells grew rapidly in the hydrothermal vent environment, undergoing Darwinian evolution and diversification. These primordial hyperthermophiles, presumably the first life, obtained food and energy directly from the vent environment. However, such a situation was self-limiting, so the early cells evolved their own mechanisms for generating metabolic energy and synthesizing the molecules necessary for their reproduction. The earliest fossil record (≥ 3.5 Ga) of biotic activity is preserved in the Archean hydrothermal and sedimentary rocks of the Nuvvuagittuq Craton of Canada, the Isua Craton of Greenland, the Pilbara Craton of Australia, the Kaapvaal Craton of South Africa, and the Singhbhum Craton of India in the form of the carbonaceous remains of microbial cells, cellular microfossils, and stromatolites. These microscopic fossils provide crucial evidence of the origin and early evolution of prokaryotic cells, beginning with hyperthermophiles. Molecular phylogenetic analysis suggests that both domains of life ¬– Bacteria and Archaea probably split from the last universal common ancestor (LUCA), a hyperthermophilic organism. In the younger sequences of these Archean cratons, two kinds of photosynthetic bacteria, anoxygenic green sulfur bacteria, and oxygenic cyanobacteria, appeared in quick succession from the thermophilic ancestor, indicating a shift of niche from a benthic to a planktonic, with reduced thermotolerance. The development of anoxygenic and oxygenic photosynthesis would have allowed life to escape the hydrothermal setting and invade a newly evolved habitat—broad continental shelves to tap solar energy. Cyanobacteria invaded the global ocean, turned it into blue and green, produced oxygen for the first time, and left their signatures in the carbonates and stromatolites.
Subject: Earth Sciences, Palaeontology Keywords: protein/RNA world: plasma membrane; cytoplasm; gene regulation; virus world; pre-retro virus; emergence of DNA; transcription and replication; first cells; hyperthermophiles; LUCA; Bacteria and Archaea; anoxygenic bacteria; oxygenic bacteria; global distribution of cyanobacteria
Online: 12 February 2020 (03:25:07 CET)
The emergence of proteins in the prebiotic world was a watershed event at the origin of life. With their astonishing versatility, the protein enzymes catalyzed crucial biochemical reactions within protocells into more complex biomolecules in diverse metabolic pathways, whereas structural proteins provided strength and permeability in the cell membrane. Five major biochemical innovations followed in succession after availability of various kinds of protein molecules during decoding and translation of mRNAs. These are: (1) the modification of the phospholipid membrane into the plasma membrane; (2) the origin of primitive cytoplasm; (3) primitive gene regulation; (4) the beginnings of the virus world; and (5) the advent of DNA. The creative role of viruses during prebiotic synthesis led to the origin of the DNA world, when DNA replaced mRNA as the major genome of the protocells. With the advent of DNA, replication of information was entirely dissociated from its expression. Because DNA is much more stable than mRNA with more storage capacity, it is a superb archive for information systems in the form of base sequences. DNA progressively took over the replicative storage function of mRNA, leaving the latter for protein synthesis. Genetic information began to flow from DNA to mRNA to protein in a two-step process involving transcription and translation. In the biological stage, DNA replication was central to the binary fission of the first cell, orchestrated by the duplication of genomes and then the division of the parent cell into two identical daughter cells. With the onset of binary fission, the population of primitive cells grew rapidly in the hydrothermal vent environment, undergoing Darwinian evolution and diversification by mutation. The habitat of the earliest fossil record (≥ 3.5 Ga) from the Archean sedimentary rocks of Canada, Greenland, Australia, South Africa, and India offers a new window on the early radiation of microbial life. The development of anoxygenic and then oxygenic photosynthesis from early hyperthermophiles would have allowed life to escape the hydrothermal setting to the mesophilic global ocean.