REVIEW | doi:10.20944/preprints201806.0451.v1
Subject: Life Sciences, Biotechnology Keywords: aroma; bioflavour; Saccharomyces cerevisiae; synthetic biology; yeast; Yeast 2.0
Online: 27 June 2018 (15:24:02 CEST)
Abstract: Yeast – especially Saccharomyces cerevisiae – have long been a preferred workhorse for the production of numerous recombinant proteins and other metabolites. S. cerevisiae is a noteworthy aroma compound producer, and has also been exploited to produce foreign bioflavour compounds. In the past few years, important strides have been made in unlocking the key elements in the biochemical pathways involved in the production of many aroma compounds. The expression of these biochemical pathways in yeast often involves the manipulation of the host strain to direct the flux towards certain precursors needed for the production of the given aroma compound. This review highlights recent advances in the bioengineering of yeast – including S. cerevisiae – to produce aroma compounds and bioflavours. To capitalise on recent advances in synthetic yeast genomics, this review presents yeast as a significant producer of bioflavours in a fresh context and proposes new directions for combining engineering and biology principles to improve the yield of targeted aroma compounds.
ARTICLE | doi:10.20944/preprints202012.0444.v1
Subject: Biology, Anatomy & Morphology Keywords: novel rumen yeast; screening; isolation; biomass of yeast; cellulase enzyme
Online: 18 December 2020 (07:26:28 CET)
We hypothesized that rumen fluid with yeast producing cellulase enzyme can occur and also produces a high biomass compared to S. cerevisiae. Therefore, the aim of this study was to screen and isolate yeast from rumen fluids with an experimental design method. We optimized a fermentation medium containing sugarcane molasses as a carbon source and urea as a nitrogen source to measure the efficiency of biomass production and cellulase activity. Two fistulated-crossbred Holstein Friesian steers, averaging 350 ± 20 kg body weight, were used to screen and isolate ruminal yeast. The two experiments were designed. A 12 × 3 × 3 factorial was used in a completely randomized design to determine biomass and carboxymethyl cellulase activity. Factor A was isolated yeasts and S. cerevisiae. Factor B was sugarcane molasses (M) concentration. Factor C was urea (U) concentration. Potential yeast was selected for identified and analyzed as a 4 × 3 factorial use in a completely randomized design including. Factor A was incubation times. Factor B was isolated yeast strains including code H-KKU20 (as P. kudriavzevii-KKU20), I-KKU20 (C. tropicalis-KKU20), and C-KKU20 (as Galactomyces sp.-KKU20). Isolation was under aerobic conditions, resulting in a total of 11 different colonies. We noted two appearances of colonies including, asymmetric colonies of isolated yeast (indicated as A, B, C, E, and J) and ovoid colonies (coded as D, F, G, H, I, and K). The highest biomass was observed in three yeasts including codes H, I, and C-KKU20 when inoculated in 25% molasses with 1% urea (M25+U1) (p <0.01). The highest CMCase activity was observed in yeast code H-KKU20 when inoculated in all media solutions (p <0.01). Ruminal yeasts strains H-KKU20, I-KKU20, and C-KKU20 were selected for their ability to produce biomass and their CMCase enzyme synthesis. Identification of isolates H-KKU20 and I-KKU20 revealed that those isolates belonged to Pichia kudriavzevii-KKU20 and Candida tropicalis-KKU20, while C-KKU20 was identified as Galactomyces sp.-KKU20. Two strains provided maximum cell growth: P. kudriavzevii-KKU20 (9.78 and 10.02 Log cell/ml) and C. tropicalis-KKU20 (9.53 and 9.6 Log cells/ml) at 60 and 72 h of incubation time, respectively. The highest ethanol production was observed in S. cerevisiae: 76.4, 77.8, 78.5, and 78.6 g/L at 36, 48, 60, and 72 h of incubation time, respectively (p <0.01). The P. kudriavzevii-KKU20 yielded the least reducing sugar about 30.6 and 29.8 g/L at 60 and 72 h of incubation time, respectively. It could be concluded that screening and isolating yeast from rumen fluids resulted in 11 different characteristics of yeasts. The first novel yeasts discovered in the rumen fluid of cattle were Pichia kudriavzevii-KKU20, Candida tropicalis-KKU20, and Galactomyces sp.- KKU20. P. kudriavzevii-KKU20 had higher results than the other yeasts in terms of biomass production, cellulase enzyme activity, and cell number.
REVIEW | doi:10.20944/preprints201812.0001.v1
Online: 2 December 2018 (10:13:38 CET)
This review summarizes the use of CRISPR system in yeasts, identifying advantages and disadvantages of its applications. 39 articles were evaluated including 12 articles that discussed the advantages of new CRISPR systems that improved the initial system, and another 27 were evaluated, among these: three were applications in Cryptococcus neoformans, four in candida sp., three in Schizosaccharomyces pombe, nine in Saccharomyces cerevisiae, four in Yarrowia lipolytica, and four in industrially important yeasts such as Pichia pastoris and Saccharomyces pastorianus. It was concluded that the CRISPR system is one of the most versatile genetic editing systems available nowadays. It can be applied in different organisms for several effects including gene knock-outs, performing point mutations, gene expression, or even applying multiple edition operations in several genes. However, we recognize that numerous studies lack a control group of the mutated strains, which leaves many questions unanswered. For instance, the extent and precision of this techniques, it also represents a risk to biosecurity standards. Therefore, this review shows the compilation of CRISPR system information, which could be used to generate different alternatives in the industry and clinical fields.
REVIEW | doi:10.20944/preprints202107.0237.v1
Online: 12 July 2021 (09:38:48 CEST)
Microorganisms including actinomycetes, archaea, bacteria, fungi, yeast, and micro algae are the auspicious source of vital bioactive compounds. In this review, the existing state of the art re-garding antimicrobial molecules from microorganisms has been summarized. The potential an-timicrobial compounds from actinomycetes, particularly Streptomyces sp.; archaea; fungi including endophytic and marine-derived fungi, mushroom; yeast, and microalgae were briefly described. Furthermore, this review briefly summarized the activity and mode of action of bacteriocins, a ribosomally synthesized antimicrobial peptides product of Eurotium sp., Streptomyces parvulus, S. thermophiles, Lactococcus lactis, etc. Bacteriocins have inherent properties such as targeting multi-ple-drug resistant pathogens, which allows them to be considered next-generation antibiotics. Similarly, Glarea lozoyensis derived antifungal lipohexpeptides i.e., pneumocandins, inhibits 1,3-β-glucan synthase of the fungal cell wall and acts as a precursor for the synthesis of caspo-fungin, is also elaborated. In conclusion, this review highlights the possibility of using microor-ganisms as an antimicrobial resource for biotechnological, nutraceutical, and pharmaceutical ap-plications. However, more investigations are still required to separate, purify, and characterize these bioactive compounds and transfer these primary drugs into clinically approved antibiotics.
ARTICLE | doi:10.20944/preprints202102.0182.v1
Subject: Life Sciences, Biochemistry Keywords: yeast; anhydrobiosis; dehydration-rehydration; metabolism; mitochondria
Online: 8 February 2021 (10:39:47 CET)
Anhydrobiosis is the state of life when cells get into waterless conditions and gradually cease their metabolism. In this study, we determined the sequence of events in Saccharomyces cerevisiae energy metabolism during processes of dehydration and rehydration. The intensities of respiration and acidification of the medium, the amounts of Phenyldicarbaundecaborane (PCB-) bound to yeast membranes, and the capabilities of cells to accumulate K+ were assayed using electrochemical monitoring system, and intracellular content of ATP was measured using bioluminescence assay. Mesophilic, semi-resistant to desiccation S. cerevisiae strain 14 and thermotolerant, very resistant to desiccation S. cerevisiae strain 77 cells were compared. After 22 h of drying it was possible to restore the respiration activity of very resistant to desiccation strain 77 cells, especially when glucose was available. PCB- binding also indicated considerably higher metabolic activity of dehydrated S. cerevisiae strain 77 cells. Electrochemical K+ content and medium acidification assays indicated that permeabilization of the plasma membrane in cells of both strains started almost simultaneously, after 8-10 h of desiccation, but semi-resistant strain 14 cells were longer keeping K+ gradient and stronger acidifying the medium. For both cells, the fast rehydration in water was less efficient compared to reactivation in the growth medium, indicating the need for nutrients for the recovery. Higher viability of strain 77 cells after rehydration could be due to the higher stability of their mitochondria.
Online: 6 July 2020 (04:08:10 CEST)
Yeast extract is widely used in different food industries as a flavoring agent or vitamin supplement. In this study, a process was optimized for the production of yeast extract from Baker’s yeast (Saccharomyces cerevisiae). A glass vessel stirred fermenter was used for the cultivation of yeast biomass. The effect of various physical and chemical factors was evaluated on the production of yeast cells and optimum conditions for the production of maximum yeast biomass were determined. The optimum growth was obtained at 30ºC with pH 4.5 using molasses as a substrate supplemented with urea at 150rpm. Yeast cells were then separated by centrifugation and ruptured and autolysis was observed to be the most feasible method. Among various method employed to dry the yeast extract, spray dryer appeared as most efficient one. Yeast extract obtained after drying was subjected to different analyses and compared with commercial yeast extract. The produced yeast extract was applied in media preparation to grow different microorganisms including yeast, bacteria and fungi and considerable growth was observed. These results indicated that the developed process is a cost effective alternate approach for the production of yeast extract.
ARTICLE | doi:10.20944/preprints201909.0113.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: native yeast; biocontrol; fungal pathogens; VOCs
Online: 11 September 2019 (02:55:31 CEST)
Changes in consumer expectations have led to increasing demand for novel plant protection strategies, in order to reduce the application of chemical products, reduce the occurrence of new pests and the impact that all these actions generate in the environment. In recent years there have been numerous investigations related to biological control and the use of microorganisms as new control strategies. As part of integrated disease management, antagonistic microorganisms have been investigated lately and presented great interest. Such microorganisms can be applied in conventional and in organic farming as biological control agents (BCA). Many of these microorganisms are present in the microbial ecology generating interactive associations between surrounding microorganisms. For these reasons, it has become necessary to search new natural antimicrobial agents as alternatives to synthetic and chemical products. It has been discovered that there are microorganisms, particularly yeasts, that have antagonistic activity and different mechanisms of action, indicating that they could be interesting candidates for the development of BCA. Here, we evaluate the antagonist effect of four endophytic yeast, Cryptococcus antarcticus, Aureobasidium pullulans, Cryptococcus terrestris and Cryptococcus oeirensis over the growth of Botrytis cinerea, Monilinia laxa, Penicillium expansum and Geotrichum candidum in in vitro assays (inhibition zone diameter assay and confrontation assay).The results revealed that the four yeast strains evaluated showed antagonistic activity against the phytopathogens tested, suggesting that these yeasts produce compounds capable of inhibiting the growth of fungi and, depending on the assay, the evaluated antagonist-yeasts have differential biocontrolling-effect against the postharvest pathogens tested.
ARTICLE | doi:10.20944/preprints201812.0220.v1
Subject: Life Sciences, Other Keywords: yeast, multicellularity, adhesion, major evolutionary transition
Online: 18 December 2018 (11:15:41 CET)
Understanding how and why cells cooperate to form multicellular organisms is a central aim of evolutionary biology. Multicellular groups can form through clonal development (where daughter cells stick to mother cells after division) or by aggregation (where cells aggregate to form groups). These different ways of forming groups directly affect relatedness between individual cells, which in turn influences the degree of cooperation and conflict within the multicellular group. It is hard to study the factors that favoured multicellularity by focusing only on obligately multicellular organisms, like complex animals and plants, because the factors that favour multicellular cooperation cannot be disentangled, as cells cannot survive and reproduce independently. We propose bakers yeast, Saccharomyces cerevisiae, as an ideal model for studying the very first stages of the evolution of multicellularity. This is because it can form multicellular groups both clonally and through aggregation and uses a family of proteins called ‘flocculins’ that determine the way in which groups form, making it particularly amenable to lab experiments. We briefly review current knowledge about multicellularity in S. cerevisiae and then propose a framework for making predictions about the evolution of multicellular phenotypes in yeast based on social evolution theory. We finish by suggesting outstanding questions and potentially fruitful avenues for future research.
ARTICLE | doi:10.20944/preprints202209.0333.v1
Subject: Life Sciences, Biotechnology Keywords: rosé wine; probiotic yeast; fermentation; distillation; viability
Online: 22 September 2022 (05:44:56 CEST)
This paper reports for the first time on the production of probiotic alcoholic and non-alcoholic rosé wines with enhanced health benefits made with Saccharomyces cerevisiae var. boulardii probiotic yeast. The alcohol, sugar, volatile acidity lactic and malic acid contents were assessed for S. cerevisiae var. boulardii before and after fermentation and distillation and compared with a conventional Saccharomyces cerevisiae (ex-bayanus) yeast. The free amino nitrogen and gluconic acid concentrations in the musts were determined. Yeast viability was evaluated after fermentation and distillation as a function of time (0, 15 days, 3 months and 6 months) both at room temperature (25±0.5ºC) and refrigerator temperature (4±0.5ºC). The results obtained showed that the probiotic rosé wine produced with S. cerevisiae var. boulardii possesses the typical values and sensory attributes of other commercial wines produced with S. cerevisiae (ex-bayanus). The probiotic S. cerevisiae var. boulardii yeast survives the high alcohol content produced during fermentation and vacuum distillation. The study also showed that this probiotic rosé wine stored either at room temperature or in a refrigerator keeps its probiotic viability for at least six months, which makes it a promising for large-scale production, in which long storage times are required by both producers and consumers.
TECHNICAL NOTE | doi:10.20944/preprints202203.0146.v1
Subject: Life Sciences, Biophysics Keywords: expansion microscopy; yeast; Saccharomyces cerevisiae; super-resolution
Online: 10 March 2022 (10:51:02 CET)
The unicellular eukaryote S. cerevisiae is an invaluable resource for the study of basic eukaryotic cellular and molecular processes. However, due to its small size compared to other eukaryotic organisms the study of subcellular structures is challenging. Expansion microscopy (ExM) holds great potential to study the intracellular architecture of yeast, especially when paired with pan-labelling techniques visualising the full protein content inside cells. ExM allows to increase imaging resolution by physically enlarging a fixed sample that is embedded and cross- linked to a swellable gel followed by isotropic expansion in water. The cell wall present in fungi – including yeast – and Gram-positive bacteria is a resilient structure that resists denaturation and conventional digestion processes usually used in ExM protocols, resulting in uneven expansion. Thus, the digestion of the cell wall while maintaining the structure of the resulting protoplasts are crucial steps to ensure isotropic expansion. For this reason, specific experimental strategies are needed, and only a few protocols are currently available. We have developed a modified ExM protocol for S. cerevisiae, with 4x expansion factor, which allows the visualisation of the ultrastructure of the cells. Here, we describe the experimental procedure in detail, focusing on the most critical steps required to achieve isotropic expansion for ExM of S. cerevisiae.
ARTICLE | doi:10.20944/preprints201611.0023.v1
Subject: Life Sciences, Other Keywords: anti-yeast; enzyme inhibitors; Terminalia mantaly; Combretaceae
Online: 3 November 2016 (09:35:17 CET)
The chemical investigation of the anti-yeast methanol extract from the stem bark of Terminalia mantaly led to the isolation of seven compounds: 3-O-methyl-4-O-α-rhamnopyranoside ellagic acid (1), 3-O-mehylellagic acid (2), arjungenin or 2,3,19,23-tetrahydroxyolean-12-en-28-oïc acid (3), arjunglucoside or 2,3,19,23-tetrahydroxyolean-12-en-28-oïc acid glucopyranoside (4), 2α,3α,24-trihydroxyolean-11,13(18)-dien-28-oïc acid (5), stigmasterol (6), stigmasterol 3-O-β-D-glucopyranoside (7). Their structures were established by means of spectroscopic analysis and comparison with published data. Compounds 1-5 were tested in vitro for activity against three pathogenic yeast isolates, Candida albicans, Candida parapsilosis and Candida krusei. The activity of compounds 1, 2 and 4 were comparable to that of the reference compound fluconazole (MIC values below 32 µg/ml) against the three tested yeast isolates. They were also tested for inhibitory properties against four enzymes of metabolic significance: Glucose-6-Phosphate Deshydrogenase (G6PD), human erythrocyte Carbonic anhydrase I and II (hCA I and hCA II), Glutathione S-transferase (GST). Compound 4 showed highly potent inhibitory property against the four tested enzymes with overall IC50 values below 4 µM and inhibitory constant (Ki) <3 µM.
REVIEW | doi:10.20944/preprints202106.0163.v1
Subject: Biology, Other Keywords: white biotechnology; metabolic engineering; non-conventional yeast; oleaginous yeast; cell factory; heterologous expression; biodiversity; Yarrowia lipolytica; Yarrowia clade; GMO
Online: 7 June 2021 (10:50:26 CEST)
Among non-conventional yeasts of industrial interest, the dimorphic oleaginous yeast Yarrowia lipolytica appears as one of the most attractive for a large range of white biotechnology applications, from heterologous proteins secretion to cell factories process development. The past, present and potential applications of wild type, traditionally improved or genetically modified Yarrowia lipolytica strains will be resumed, together with the wide array of molecular tools now available to genetically engineer and metabolically remodel this yeast. The present review will also provide a detailed description of Yarrowia lipolytica strains and highlight the natural biodiversity of this yeast, a subject little touched upon in most previous reviews. This work intends to fill this gap by retracing the genealogy of the main Yarrowia lipolytica strains of industrial interest, by illustrating the search for new genetic backgrounds and by providing data about the main publicly available strains in yeast collections worldwide. At last, it will focus on exemplifying how advances in engineering tools can leverage a better biotechnological exploitation of the natural biodiversity of Yarrowia lipolytica and of other yeasts from the Yarrowia clade.
ARTICLE | doi:10.20944/preprints202011.0583.v1
Subject: Life Sciences, Biochemistry Keywords: Itaconic acid; U. maydis; Metabolic engineering; Fungi; Yeast
Online: 23 November 2020 (13:47:27 CET)
Ustilago maydis, member of the Ustilaginaceae family, is a promising host for the production of several metabolites including itaconic acid. This dicarboxylate has great potential as a bio-based building block in the polymer industry, and is of special interest for pharmaceutical applications. Several itaconate overproducing Ustilago strains have been generated by metabolic and morphology engineering. This yielded stabilized unicellular morphology through fuz7 deletion, reduction of by-product formation through deletion of genes responsible for itaconate oxidation and (glyco)lipid production, and the overexpression of the regulator of the itaconate cluster ria1 and the mitochondrial tricarboxylate transporter encoded by mttA from Aspergillus terreus. In this study, itaconate production was further optimized by consolidating these different optimizations into one strain. The combined modifications resulted in itaconic acid production at theoretical maximal yield, which was achieved under biotechnologically relevant fed-batch fermentations with continuous feed.
ARTICLE | doi:10.20944/preprints202011.0237.v1
Subject: Life Sciences, Biochemistry Keywords: Saccharomyces cerevisiae; SCRaMbLE; genome evolution; industrial yeast strains
Online: 6 November 2020 (10:30:45 CET)
Genome-scale engineering and custom synthetic genomes are reshaping the next generation of industrial yeast strains. The Cre-recombinase mediated chromosomal rearrangement mechanism of designer synthetic Saccharomyces cerevisiae chromosomes, known as SCRaMbLE, is a powerful tool which allows rapid genome evolution upon command. This system is able to generate millions of novel genomes with potential valuable phenotypes, but the excessive loss of essential genes often results in poor growth or even the death of cells with useful phenotypes. In this study we expanded the versatility of SCRaMbLE to industrial strains, and evaluated different control measures to optimise genomic rearrangement, whilst limiting cell death. To achieve this, we have developed RED (Rapid Evolution Detection), a simple colorimetric plate-assay procedure to rapidly quantify the degree of genomic rearrangements within a post-SCRaMbLE yeast population. RED-enabled semi-synthetic strains were mated with haploid progeny of industrial yeast strains to produce stress tolerant heterozygous diploid strains. Analysis of these heterozygous strains with the RED-assay, genome sequencing and custom bioinformatics scripts demonstrated a correlation between RED-assay frequencies and physical genomic rearrangements. Here we show that RED is a fast and effective method to evaluate optimal SCRaMbLE induction times of different Cre-recombinse expression systems for the development of industrial strains.
Subject: Life Sciences, Biophysics Keywords: non-ionizing radiation; millimeter waves; novel biomedical applications; yeast; non-invasive devices
Online: 17 September 2020 (07:08:47 CEST)
Nonionizing millimeter-waves (MMW) are reported to interact with cells in a variety of ways. Possible mechanisms of the inhibited cell division effect were investigated using 85-105 GHz MMW irradiation within the ICNIRP (International Commission on Non-Ionizing Radiation Protection) non-thermal 20 mW/cm2 safety standards. ~1.0 mW/cm2 exposure over 5-6 hours treatment on 50 cells/μl samples of Saccharomyces cerevisiae model organism, resulted in 62% growth rate reduction compared to control (sham). The effect was specific for 85-105 GHz range and energy dose and cell density dependent. Irradiation of wild type and Δrad52 (DNA damage repair gene) deletion cells presented no differences of colony growth profiles indicating non-thermal MMW treatment does not cause genetic alterations. Dose versus response relations studied using a standard horn antenna (~1.0 mW/cm2) and compared to that of a compact waveguide (17.17 mW/cm2) for increased power delivery resulted in complete termination of cell division via non-thermal processes supported by temperature rise measurements. Combinations of MMW mediated Structure Resonant Energy Transfer (SRET), membrane modulations eliciting signaling effects, and energetic resonance with biomolecules were indicated to be responsible for the observations reported. Our results provide novel mechanistic insights enabling innovative applications of nonionizing radiation procedures for eliciting targeted biomedical outcomes.
ARTICLE | doi:10.20944/preprints201903.0119.v1
Subject: Chemistry, Food Chemistry Keywords: effervescence; bubbles; protein; yeast invertase; foamability; wine quality
Online: 11 March 2019 (08:04:48 CET)
The appearance of bubbles and foam can influence the likeability of a wine even before its consumption. Since foams are essential to visual and taste attributes of sparkling wines, it is of great importance to understand which compounds affect bubbles and foam characteristics. The aim of this work was to investigate the effect of interactions among proteins, amino acids, and phenols on the characteristics of foam in sparkling wines by using synchronous fluorescence spectroscopy techniques. Results has shown that several compounds present in sparkling wines influence foam quality differently, and importantly, highlighted how the interaction of those compounds might result in different effects on foam parameters. Amongst the results, mannoproteins were found to be most likely to promote foam and collar stability, while phenols were likely to increase the ratio of small bubbles and collar height in the foam matrix. In summary, this work contributes to a better understanding of the effect of wine compounds on foam quality as well as the effect of the interactions between those compounds.
ARTICLE | doi:10.20944/preprints201810.0288.v1
Subject: Life Sciences, Molecular Biology Keywords: red yeast rice; berberis aristate; morus alba; PCSK9
Online: 15 October 2018 (07:49:55 CEST)
Proprotein convertase subtilisin/kexin type 9 (PCSK9) is the key regulator of low-density lipoprotein cholesterol (LDL-C) plasma levels. We previously observed that treatment of dyslipidemic subjects with nutraceutical combination containing red yeast rice (monacolin K 3.3 mg), Berberis aristata cortex extract (Berberine 531.25 mg) and Morus alba leaves extract (1-deoxynojirimycin 4 mg) (LopiGLIK®) did not alter the plasma PCSK9 levels. Thus, the aim of the present study was to investigate the effect of these three components on PCSK9 expression in HepG2 cell line in relationship to their effects on LDL-C cellular uptake. HepG2 cell line were incubated with Berberis aristata cortex extract (BCE), red yeast rice (RYR) and Morus alba leaves extract (MLE) alone or in combination for 24 h. RYR (50 µg/mL) increased PCSK9 protein expression (WB and ELISA assays), PCSK9 mRNA and its promoter activity. BCE (40 µg/mL) reduced PCSK9 expression, mRNA levels and promoter activity. MLE determined a concentration-dependent inhibition of PCSK9 at mRNA and protein levels, with a maximal reduction at 1 mg/mL; no significant changes in PCSK9 promoter activity were found. MLE also downregulates the expression of fatty acid synthase and HMG-CoA reductase mRNA levels. The combination of RYR, BCE and MLE reduced PCSK9 at mRNA, protein, and promoter activity. Finally, this combination induced the LDL receptor and LDL-C uptake by HepG2 cells. In conclusion, the positive effect of MLE on PCSK9 supports the rational of using this nutraceutical combination to control hyperlipidemic conditions.
REVIEW | doi:10.20944/preprints202111.0458.v1
Online: 24 November 2021 (13:10:22 CET)
Nicotinamide adenine dinucleotide (NAD+) is an essential molecule involved in various metabolic reactions, acting as an electron donor in the electron transport chain and as a co-factor for NAD+-dependent enzymes. In the early 2000s, reports that NAD+ declines with aging introduced the notion that NAD+ metabolism is globally and progressively impaired with time. Since then, NAD+ became an attractive target for potential pharmacological therapies aiming to boost NAD+ levels to promote vitality and protect against age-related diseases. This review summarizes and discusses a collection of studies that report the levels of NAD+ with aging in different species (i.e., yeast, C. elegans, rat, mouse, monkey, and human) to determine whether the notion that overall NAD+ levels decrease with aging stands true. We find that despite systematic claims of overall changes in NAD+ levels with aging, the evidence to support it is very limited and often restricted to a single tissue or cell type. This is particularly true in humans, where the development of NAD+ levels during aging is still poorly characterized. There is a need for much larger, preferably longitudinal, studies aimed to assess how NAD+ levels develop with aging in various tissues. This will strengthen our conclusions on NAD+ during aging and should provide a foundation for better pharmacological targeting of relevant tissues.
REVIEW | doi:10.20944/preprints201612.0061.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: alcohol; aroma; bioengineering; flavour; synthetic genomics; taste; wine; yeast
Online: 10 December 2016 (09:09:54 CET)
A perfectly balanced wine can be said to create a symphony in the mouth. To achieve the sublime, both in wine and music, requires imagination and skilled orchestration of artistic craftmanship. For wine, inventiveness starts in the vineyard. Similar to a composer of music, the grapegrower produces grapes through a multitude of specifications to achieve a quality result. Different Vitis vinifera grape varieties allow the creation of wine of different genres. Akin to a conductor of music, the winemaker decides what genre to create and considers resources required to realise the grape’s potential. A primary consideration is the yeast: inoculate the grape juice or leave it ‘wild’; which specific or combined Saccharomyces strain(s) should be used; or proceed with a non-Saccharomyces species? Whilst the various Saccharomyces and non-Saccharomyces yeasts perform their role during fermentation, the performance is not over until the ‘fat lady’ (S. cerevisiae) has sung (i.e. the grape sugar has been fermented to specified dryness and alcoholic fermentation is complete). Is the wine harmonious or discordant? Will the consumer demand an encore and make a repeat purchase? Understanding consumer needs lets winemakers orchestrate different symphonies (i.e. wine styles) using single- or multi-species ferments. Some consumers will choose the sounds of a philharmonic orchestra comprising a great range of diverse instrumentalists (as is the case with wine created from spontaneous fermentation); some will prefer to listen to a smaller ensemble (analogous to wine produced by a selected group of non-Saccharomyces and Saccharomyces yeast); and others will favour the well-known and reliable superstar soprano (i.e. S. cerevisiae). But what if a digital music synthesiser ‒ such as a synthetic yeast ‒ becomes available that can produce any music genre with the purest of sounds by the touch of a few buttons? Will synthesisers spoil the character of the music and lead to the loss of the much-lauded romantic mystique? Or will music synthesisers support composers and conductors to create novel compositions and even higher quality performances that will thrill audiences? This article explores these and other relevant questions in the context of winemaking and the role that yeast and its genomics play in the betterment of wine quality.
REVIEW | doi:10.20944/preprints202201.0084.v1
Subject: Life Sciences, Biotechnology Keywords: hybrid; lager; yeast; introgression; interspecific; domestication; phylogeny; brewing; molecular; genomics
Online: 6 January 2022 (11:55:13 CET)
: Microbiology has long been a keystone in fermentation and the utilization of yeast biology rein-forces molecular biotechnology as the pioneering frontier in brewing science. Consequently, modern understanding of the brewer’s yeast has faced significant refinement over the last few decades. This publication presents a condensed summation of Saccharomyces species dynamics with an emphasis on the relationship between traditional ale yeast, Saccharomyces cerevisiae, and the interspecific hybrids used in lager beer production, S. pastorianus. Introgression from other Sac-charomyces species is also touched on. The unique history of Saccharomyces cerevisiae and Saccharo-myces hybrids are exemplified by recent genomic sequencing studies aimed at categorizing brewing strains through phylogeny and redefining Saccharomyces species boundaries. Phylogenetic investigations highlight the genomic diversity of Saccharomyces cerevisiae ale strains long known to brewers by their fermentation characteristics and phenotypes. Discoveries of genomic contribu-tions from interspecific Saccharomyces species into the genome of S. cerevisiae strains is ever more apparent with increased investigations on the hybrid nature of modern industrial and historical fermentation yeast.
REVIEW | doi:10.20944/preprints202110.0079.v1
Subject: Life Sciences, Biotechnology Keywords: genetic switch; yeast; synthetic transcription factor; synthetic promoter; directed evolution
Online: 5 October 2021 (11:19:46 CEST)
Genetic switches can be utilized for many purposes in synthetic biology including the assembly of complex genetic circuits to achieve sophisticated cellular systems and the construction of biosensors for real-time monitoring of intracellular metabolite concentrations. Although genetic switches have mainly been developed in prokaryotes to date, eukaryotic genetic switches are increasingly being reported as both rational and irrational engineering technologies mature. In this review, we describe genetic switches in yeast based on synthetic transcription factors and/or synthetic promoters. We also discuss directed evolution technologies for the rapid and robust construction of yeast genetic switches.
ARTICLE | doi:10.20944/preprints202010.0484.v1
Subject: Biology, Anatomy & Morphology Keywords: inorganic polyphosphate; VTC4; knockout mutant; oxidative stress; gene expression; yeast
Online: 23 October 2020 (10:42:43 CEST)
Inorganic polyphosphate (polyP) is an important factor of stress tolerance in microbial cells. In yeast, the major enzyme of polyP biosynthesis is Vtc4, a subunit of the vacuole transporter chaperone (VTC) complex. In this study, we demonstrated that Vtc4 knockout in Saccharomyces cerevisiae not only decreased polyP content but also caused shifts in the composition of the intracellular polyP pool and changed the stress tolerance profile. In the mutant S. cerevisiae, the level of short-chain acid-soluble polyPs was decreased nearly 10-fold, whereas that of longer acid-insoluble polyPs was decreased only 2-fold, suggesting the existence of other enzymes compensating the production of long-chain polyPs. The Δvtc4 mutant showed inhibition of Mg2+-dependent phosphate uptake and decreased resistance to alkaline stress but increased tolerance to oxidation and heavy metal ions, especially Mn2+. Quantitative PCR revealed the upregulation of the DDR2 gene implicated in multiple stress responses and downregulation of PHO84 encoding a phosphate and Mn2+ transporter, which could account for the effects on phosphate uptake and Mn2+-related stress response in the Δvtc4 mutant. Our study indicates that short-chain polyPs, plays an important role in the regulation of stress response in yeast.
ARTICLE | doi:10.20944/preprints202104.0430.v1
Subject: Life Sciences, Biochemistry Keywords: lactic acid bacteria; probiotic; yeast; acrylamide; amidase; degradation; Response Surface Methodology
Online: 16 April 2021 (10:32:49 CEST)
Acrylamide (AA) present in food is considered a harmful compound for humans, but it exerts impact on microorganisms too. The aim of the study was to evaluate the impact of AA (at conc. 0-10 µg/mL) on the growth of bacteria (Leuconostoc mesenteroides, Lactobacillus acidophilus LA-5) and yeasts (Saccharomyces cerevisiae, Kluyveromyces lactis var. lactis), which naturally occur in food products. Moreover, we decided to verify whether these microorganisms could decompose acrylamide. Our results proved that AA can stimulated the growth of L. acidophilus and K. lactis. We have also reported, to the best of our knowledge for the first time, that probiotic strain of bacteria L. acidophilus LA-5 is able to degrade AA by amidase production and hence can utilize AA as a source of carbon and nitrogen if they lack in the environment. The conducted Response Surface Methodology indicated that pH as well as incubation time and temperature significantly influenced the amount of ammonia released from acrylamide by the bacteria. Concluding, our studies suggest that some strains of bacteria present in milk fermented products can exert additional beneficial impact by acrylamide degradation and preventing against its harmful impact on human body and other members of intestinal microbiota.
ARTICLE | doi:10.20944/preprints202103.0452.v1
Subject: Biology, Anatomy & Morphology Keywords: fission yeast; kinesin-14; RNA-binding protein; mitotic spindle; heat stress
Online: 17 March 2021 (16:52:41 CET)
Cells form a bipolar spindle during mitosis to ensure accurate chromosome segregation. Proper spindle architecture is established by a set of kinesin motors and microtubule-associated proteins. In most eukaryotes, kinesin-5 motors are essential for this process, and genetic or chemical inhibition of their activity leads to the emergence of monopolar spindles and cell death. However, these deficiencies can be rescued by simultaneous inactivation of kinesin-14 motors, as they counteract kinesin-5. We conducted detailed genetic analyses in fission yeast to understand the mechanisms driving spindle assembly in the absence of kinesin-5. Here we show that deletion of the nrp1 gene, which encodes a putative RNA-binding protein with unknown function, can rescue temperature sensitivity caused by cut7-22, a fission yeast kinesin-5 mutant. Interestingly, kinesin-14/Klp2 levels on the spindles in the cut7 mutants were significantly reduced by the nrp1 deletion, although the total levels of Klp2 and the stability of spindle microtubules remained unaffected. Moreover, RNA-binding motifs of Nrp1 are essential for its cytoplasmic localization and function. We have also found that a portion of Nrp1 is spatially and functionally sequestered by chaperone-based protein aggregates upon mild heat stress and limits cell division at high temperatures. We propose that Nrp1 might be involved in post-transcriptional regulation through its RNA-binding ability to promote the loading of Klp2 on the spindle microtubules.
ARTICLE | doi:10.20944/preprints201805.0234.v1
Subject: Biology, Other Keywords: non-coding RNA; telomerase RNA; secondary structure; synteny; homology search; yeast
Online: 16 May 2018 (11:58:28 CEST)
The telomerase RNA in yeasts is large, usually >1000 nt, and contains functional elements that have been extensively studied experimentally in several disparate species. Nevertheless, they are very difficult to detect by homology-based methods and so far have escaped annotation in the majority of the genomes of Saccharomycotina. This is a consequence of sequences that evolve rapidly at nucleotide level, are subject to large variations in size, and are highly plastic with respect to their secondary structures. Here we report on a survey that was aimed at closing this gap in RNA annotation. Despite considerable efforts and the combination of a variety of different methods, it was only partially successful. While 27 new telomerase RNAs were identified, we had to restrict our efforts to the subgroup Saccharomycetacea because even this narrow subgroup was diverse enough to require different search models for different phylogenetic subgroups. More distant branches of the Saccharomycotina still remain without annotated telomerase RNA.
ARTICLE | doi:10.20944/preprints202208.0428.v1
Subject: Life Sciences, Biotechnology Keywords: ethanol stress; ethanol tolerance; industrial yeast strains; high-gravity fermentation; TRP1; MSN2
Online: 25 August 2022 (07:39:56 CEST)
The stress imposed by ethanol to Saccharomyces cerevisiae cells are one of the most challenging limiting factors in industrial fuel-ethanol production. Consequently, the toxicity and tolerance to high ethanol concentrations has been the subject of extensive research, allowing the identification of several genes important for increasing the tolerance to this stress factor. However, most studies were performed with well characterized laboratory strains, and how the results obtained with these strains work in industrial strains remains unknown. In the present work we have tested three different strategies known to increase ethanol tolerance by laboratory strains in an industrial fuel-ethanol producing strain: overexpression of the TRP1 or MSN2 genes, or overexpression of a truncated version of the MSN2 gene. Our results show that the industrial CAT-1 strain tolerates up to 14% ethanol, and indeed the three strategies increased its tolerance to ethanol. When these strains were subjected to fermentations with high sugar content and cell-recycle, simulating the industrial conditions used in Brazilian distilleries, only the strain with overexpression of the truncated MSN2 gene showed improved fermentation performance, allowing the production of 16% ethanol from 33% of total reducing sugars present in sugarcane molasses. Our results highlight the importance of testing genetic modifications in industrial yeast strains under industrial conditions in order to improve the production of industrial fuel ethanol by S. cerevisiae.
ARTICLE | doi:10.20944/preprints202112.0242.v1
Subject: Life Sciences, Biochemistry Keywords: VHL; von Hippel-Lindau syndrome; ubiquitination; hypoxia; testis; yeast two-hybrid (Y2H)
Online: 14 December 2021 (14:59:05 CET)
Functional impairment of the von Hippel-Lindau (pVHL) tumor suppressor is causative of a familiar increased risk to develop cancer. As E3 substrate recognition particle, pVHL marks for degradation the hypoxia inducible factor 1α (HIF-1α) in normoxic conditions, thus acting as a key regulator of both acute and chronic cell adaptation to hypoxia. Further evidence showed pVHL to also play relevant roles in microtubules stabilization, participate in the formation of the extracellular matrix, as well as to regulate cell senescence and apoptosis. Male mice model carrying VHL gene conditional knockout present significative abnormalities in testis development paired with defects in spermatogenesis and infertility, indicating that pVHL exerts testis-specific roles, at least in mice. Here, we describe 55 novel interactors of the human pVHL obtained by testis-tissue library screening. We show that pVHL interacts with multiple human proteins directly involved in spermatogenesis and reproductive metabolism, suggesting that, in addition to its role in cancer formation, pVHL may be pivotal in the correct gonads development also in human.
ARTICLE | doi:10.20944/preprints202107.0127.v1
Subject: Life Sciences, Biochemistry Keywords: Actinobacillus succinogenes; Basfia succiniciproducens; succinic acid; lactose concentrate; yeast extract; platform chemical
Online: 6 July 2021 (09:28:31 CEST)
The aim of this study was to investigate succinic acid production from lactose concentrate, a by-product of cheese-making, using Actinobacillus succinogenes and Basfia succiniciproducens. Although the capability of these strains to metabolize different sugars is already known, their application in the conversion of lactose bears high potential for optimization. With regard to B. succiniciproducens this approach is completely novel. In particular the influence of the mediums sugar concentration and its supplementation with yeast extract to prevent a lack of proteins and vitamins were examined. Lactose based media containing sugar concentrations between 20 and 65 g L-1 and 5 g L-1 yeast extract were fermented, whereby both strains showed comparable performances. The best results in succinic acid yield and acid concentration, 0.57 g g-1 initial sugar and 23 g L1, were achieved at an initial sugar concentration of 43 g L-1. The necessity of yeast extract was demonstrated using the sugar optimized medium without supplementation. As a result, yield and concentration of succinic acid dropped to 0.34 g g-1 and 13 g L-1, the sugar consumption decreased from more than 99 to less than 55 %. Therefore the supplementation amount of 5 g L-1 yeast extract can be regarded as well-balanced.
ARTICLE | doi:10.20944/preprints202011.0032.v3
Subject: Life Sciences, Biochemistry Keywords: Non-ionizing Radiation; Millimeter waves; Novel biomedical applications; Yeast; Non-invasive devices
Online: 16 April 2021 (14:52:04 CEST)
Nonionizing millimeter-waves (MMW) interact with cells in a variety of ways. Here the inhibited cell division effect was investigated using 85-105 GHz MMW irradiation within the ICNIRP (International Commission on Non-Ionizing Radiation Protection) non-thermal 20 mW/cm2 safety standards. Irradiation using a power density of about 1.0 mW/cm2 , SAR over 5-6 hours on 50 cells/μl samples of Saccharomyces cerevisiae model organism resulted in 62% growth rate reduction compared to the control (sham). The effect was specific for 85-105 GHz range, and was energy and cell density dependent. Irradiation of wild type and Δrad52 (DNA damage repair gene) deleted cells presented no differences of colony growth profiles indicating non-thermal MMW treatment does not cause permanent genetic alterations. Dose versus response relations studied using a standard horn antenna (~1.0 mW/cm2) and compared to that of a compact waveguide (17.17 mW/cm2) for increased power delivery resulted in complete termination of cell division via non-thermal processes supported by temperature rise measurements. We have shown that non-thermal MMW radiation has potential for future use in treatment of yeast related diseases and other targeted biomedical outcomes.
ARTICLE | doi:10.20944/preprints202103.0132.v1
Subject: Life Sciences, Biochemistry Keywords: Wine yeast; malic acid; pH; breeding; Malo Lactic Fermentation; Marker Assisted Selection
Online: 3 March 2021 (12:43:08 CET)
Background Natural Saccharomyces cerevisiae yeast strains exhibit very large genotypic and phe-notypic diversity. Breeding programs taking advantage of this characteristic, are widely used for yeast selection in the wine industry, especially in the recent years when winemakers need to adapt their production to climate change. The aim of this work was to evaluate a Marker Assisted Se-lection (MAS) program to improve malic acid consumption capacity of Saccharomyces cerevisiae in grape juice. Methods Optimal individuals of two unrelated F1-hybrids were crossed to get a new genetic background carrying many “malic consumer” loci. Then, eleven QTLs already identified were used for implementing the MAS breeding program. Results By this way, extreme individuals able to consume more than 70% of malic acid in grape juice were selected. These individuals were tested in different enological matrixes and compared to their original parental strains. They greatly reduced the malic acid content at the end of alcoholic fermentations, they appeared to be robust to the environment and accelerate the ongoing of malo-lactic fermentations by Oenococcus oeni. Conclusions This study illustrates how MAS can be efficiently used for selecting industrial Saccharomyces cerevisiae strains with outlier properties for winemaking.
ARTICLE | doi:10.20944/preprints201910.0060.v1
Subject: Biology, Other Keywords: fission yeast; microtubule polymerase; xmap215/tog; mitotic spindle; spindle pole body; kinetochore
Online: 7 October 2019 (11:02:36 CEST)
Proper bipolar spindle assembly underlies accurate chromosome segregation. A cohort of microtubule-associated proteins orchestrates spindle microtubule formation in a spatiotemporally coordinated manner. Among them, the conserved XMAP215/TOG family of microtubule polymerase plays a central role in spindle assembly. In fission yeast, two XMAP215/TOG members, Alp14 and Dis1, share essential roles in cell viability; however how these two proteins functionally collaborate remains undetermined. Here we show the functional interplay and specification of Alp14 and Dis1. Creation of new mutant alleles of alp14, which display temperature sensitivity in the absence of Dis1, enabled us to conduct detailed analyses of a double mutant. We have found that simultaneous inactivation of Alp14 and Dis1 results in early mitotic arrest with very short, fragile spindles. Intriguingly, these cells often undergo spindle collapse, leading to a lethal “cut” phenotype. By implementing an artificial targetting system, we have shown that Alp14 and Dis1 are not functionally exchangeable and as such are not merely redundant paralogues. Intriguingly, while Alp14 promotes microtubule nucleation, Dis1 does not. Our results uncover that the intrinsic specification, not the spatial regulation, between Alp14 and Dis1 underlies the collaborative actions of these two XMAP215/TOG members in mitotic progression, spindle integrity and genome stability.
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/preprints201909.0340.v1
Subject: Life Sciences, Biotechnology Keywords: conjugation; solid media; saccharomyces cerevisiae; trans-kingdom; escherichia coli; pta-mob; yeast assembly
Online: 30 September 2019 (05:08:57 CEST)
Conjugation is a bacterial mechanism for DNA transfer from a donor cell to a wide range of recipients, including both prokaryotic and eukaryotic cells. In contrast to conventional DNA delivery techniques, such as electroporation and chemical transformation, conjugation eliminates the need for DNA extraction, thereby preventing DNA damage during isolation. While most established conjugation protocols allow for DNA transfer in liquid media or on a solid surface, we developed a procedure for conjugation within solid media. Such a protocol may expand conjugation as a tool for DNA transfer to species that require semi-solid or solid media for growth. Conjugation within solid media could also provide a more stable microenvironment in which the conjugative pilus can establish and maintain contact with recipient cells for the successful delivery of plasmid DNA. Furthermore, transfer in solid media may enhance the ability to transfer plasmids and chromosomes greater than 100 kbp. Using our optimized method, plasmids of varying sizes were tested for transfer from E. coli to S. cerevisiae. We demonstrated that there was no substantial decrease in conjugation frequency as plasmid size increased—up to 138.5 kbp in length. Finally, we established an efficient PCR-based synthesis protocol to generate custom conjugative plasmids
ARTICLE | doi:10.20944/preprints202108.0020.v2
Subject: Life Sciences, Biotechnology Keywords: Bioethanol; LCA; marine fermentation; seawater; Saccharomyces cerevisiae; water footprint; bioenergy; biofuel; marine yeast; GHG
Online: 9 August 2021 (14:52:46 CEST)
Bioethanol has many environmental and practical benefits as a transportation fuel. It is one of the best alternatives to replace fossil fuels due to its liquid nature which is similar to petrol and diesel fuels traditionally used in transportation. In addition, bioethanol production technology has the capacity for negative carbon emissions which is vital for solving the current global warming dilemma. However, conventional bioethanol production takes place based on an inland site and relies on freshwater and edible crops (or land suitable for edible crop production) for production, which has led to the food vs fuel debate. Establishing a coastal marine biorefinery (CMB) system for bioethanol production that is based on coastal sites and relies on marine resources (seawater, marine biomass and marine yeast) could be the ultimate solution. In this paper, we aim to evaluate the environmental impact of using seawater for bioethanol production at coastal locations as a step towards the evaluation of a CMB system. Hence, a life cycle assessment for bioethanol production was conducted using the proposed scenario named Coastal-Seawater and compared to the conventional scenario, named Inland-Freshwater (IF). The impact of each scenario in relation to climate change, water depletion, land use and fossil depletion was studied for comparison. The coastal-seawater scenario demonstrated an improvement upon the conventional scenario in all the selected impact categories. In particular, the use of seawater in the process had a significant effect on water depletion showing an impact reduction of 31.2%. Furthermore, reductions are demonstrated in natural land transformation, climate change and fossil depletion of 5.5%, 3.5% and 4.2% respectively. This indicates the positive impact of using seawater and coastal locations for bioethanol production and encourages research to investigate the CMB system.
Subject: Life Sciences, Genetics Keywords: DNA; Chromosomes; Yeast; Tandem Repeats; Evolution; Genetic Noise; Visualization; Doublet Frequency Maps; Sequence structure
Online: 6 August 2021 (14:25:42 CEST)
The method of doublet frequency distance (DFD-) maps was applied, here, for visualization of DNA sequence structures of yeast chromosomes. The colour scale “rainbow” of the Octave programming tool is well suited for such visualization. The DFD-maps are generated by comparison of the differences in the number of all base doublets in a shifting frame with all other positions of this frame in a regarded DNA sequence section. This procedure can be applied from DNA-sections of between a few hundred bases (bps) up to a complete chromosome with a million or more bps. An orthogonal DFD-map pattern dominates all chromosomes and its parts. It can be interpreted by a large number of successive mutation events during evolution. In contrast, diagonal patterns indicate duplications of sequence sections and multiple tandem repeats. These periodic structures are found in several chromosomes and are more or less regular or noised. The larger tandem repeat in the subtelomeric region of chromosome 12 presents a characteristic example of a nested multiple-repeat structure. Its pattern in the DFD-map illustrates obviously a temporal order of duplication and mutation events leading to a hierarchical sequence architecture.
ARTICLE | doi:10.20944/preprints201912.0109.v1
Subject: Biology, Other Keywords: key words: sake; fermentation; hybrid; ginjo; ethanol; ethyl hexanoate; isoamyl acetate; yeast; saccharomyces; metabolism
Online: 9 December 2019 (03:23:15 CET)
The use of interspecific hybrids during the industrial fermentation process has been well established, positioning the frontier of advancement in brewing to capitalize on the potential of Saccharomyces hybridization. Interspecific yeast hybrids used in modern monoculture inoculations benefit from a wide range of volatile metabolites that broaden the organoleptic complexity. This is the first report of sake brewing by Saccharomyces arboricola and its hybrids. S. arboricola x S. cerevisiae direct-mating generated cryotolerant interspecific hybrids which increased yields of ethanol and ethyl hexanoate compared to parental strains, important flavor attributes of fine Japanese ginjo sake rice wine. We used hierarchical clustering heatmapping with principal component analysis for metabolic profiling and found that the low levels of endogenous amino/organic acids clustered S. arboricola apart from the S. cerevisiae industrial strains. In sake fermentations, hybrid strains showed a mosaic profile of parental strains, while metabolic analysis suggested S. arboricola had a lower amino acid net uptake than S. cerevisiae. Additionally, we found an increase in ethanolic fermentation from pyruvate and increased sulfur metabolism. Together, our results suggest S. arboricola is poised for in-depth metabolomic exploration in sake fermentation.
ARTICLE | doi:10.20944/preprints202112.0271.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: CUE; Cue5; Komagataella phaffii; lipid droplets; lipophagy; Pichia pastoris; Prl1; selective autophagy; stationary phase; yeast
Online: 16 December 2021 (12:09:07 CET)
Recently, we developed Komagataella phaffii (formerly Pichia pastoris) as a model for lipophagy, the selective autophagy of lipid droplets (LDs). We found that lipophagy pathways induced by acute nitrogen (N) starvation and in stationary (S) phase have different molecular mechanisms. Moreover, both types of lipophagy are independent of Atg11, the scaffold protein that interacts with most autophagic receptors and, therefore, is essential for most types of selective autophagy in yeast. Since yeast aggrephagy, the selective autophagy of ubiquitinated protein aggregates, is also independent of Atg11 and utilizes the ubiquitin-binding receptor, Cue5, we studied the relationship of K. phaffii Cue5 with differentially induced LDs and lipophagy. While there was no relationship of Cue5 with LDs and lipophagy under N-starvation conditions, Cue5 accumulated on LDs in S-phase and degraded together with LDs via S-phase lipophagy. The accumulation of Cue5 on LDs and its degradation by S-phase lipophagy strongly depended on the ubiquitin-binding CUE domain and Prl1, the positive regulator of lipophagy 1. However, unlike Prl1, which is required for S-phase lipophagy, Cue5 was dispensable for it suggesting that Cue5 is rather a new substrate of this pathway. We propose that a similar mechanism (Prl1-dependent accumulation on LDs) might be employed by Prl1 to recruit another ubiquitin-binding protein that is essential for S-phase lipophagy.
ARTICLE | doi:10.20944/preprints202210.0412.v1
Subject: Life Sciences, Microbiology Keywords: biolog phenotypic technology; Candida; energy-dispersive X-ray spectroscopy; genotype; multilocus DNA sequencing; one new taxon; yeast
Online: 26 October 2022 (10:15:55 CEST)
The majority of Candida species are known as non-pathogenic yeasts and rarely involved in human diseases. However, recently case reports of human infections caused by non-albicans Candida species have increased, mostly in immunocompromised hosts. Our study aimed to describe and caracterise as thoroughly as possible, a new species of the Candida genus, named here Candida massiliensis (PMML0037), isolated from a clinical sample of human sputum. We compared genetic data based on the sequences of four genetic regions: "Internal Transcribed Spacers" of rRNA, D1/D2 domains (28S large subunit rRNA) and part of the genes encoding Translation Elongation Factor 1-α and β-tubulin2, to morphological characters, from scanning electron microscopy (TM 4000 Plus, SU5000), physiological, including the results of oxidation and assimilation tests of different carbon sources by the Biolog system, and chemical mapping by Energy-Dispersive X-ray Spectroscopy. Lastly, the in vitro antifungal susceptibility profile was performed using the E-testTM exponential gradient method. The multilocus analysis supported the genetic position of Candida massiliensis (PMML0037) as a new species of the genus Candida, and the phenotypic analysis highlighted its unique morphological and chemical profile when compared to other Candida species included in the study.
ARTICLE | doi:10.20944/preprints202104.0528.v1
Subject: Life Sciences, Biochemistry Keywords: Interactomics; host-parasite-microbiome relationships; extra-intestinal effects; D-amino ac-id/SCFA-induced modulation; Yeast ubiquinone salvation.
Online: 20 April 2021 (11:12:14 CEST)
Cryptosporidiosis is a major human health concern globally. Despite well-established methods, misdiagnosis remains common. Our understanding of the cryptosporidiosis biochemical mechanism remains limited, compounding the difficulty of clinical diagnosis. Here, we used a systems biology approach to investigate the underlying biochemical interactions in C57BL/6J mice infected with Cryptosporidium parvum. Faecal samples were collected daily following infection. Blood, liver tissues and luminal contents were collected 10 days post infection (dpi). High-resolution liquid chromatography and low-resolution gas chromatography coupled with mass spectrometry were used to analyse the proteomes and metabolomes of these samples. Faeces and luminal contents were additionally subjected to 16S rRNA gene sequencing. Univariate and multivariate statistical analysis of the acquired data illustrated altered host and microbial energy pathways during infection. Glycolysis/citrate cycle metabolites were depleted, while short-chain fatty acids and D-amino acids accumulated. An increased abundance of bacteria associated with a stressed gut environment was seen. Host proteins involved in energy pathways and Lactobacillus glyceraldehyde-3-phosphate dehydrogenase were upregulated during cryptosporidiosis. Liver oxalate also increased during infection. Microbiome-parasite relationships were observed to be more influential than the host-parasite association in mediating major biochemical changes in the mouse gut during cryptosporidiosis. Defining this parasite-microbiome interaction is the first step towards building a comprehensive cryptosporidiosis model towards biomarker discovery, and rapid and accurate diagnostics.
ARTICLE | doi:10.20944/preprints202004.0429.v1
Subject: Life Sciences, Biochemistry Keywords: Aging; Almond; Chlorogenic acid; Lipid peroxidation; Mitochondria; 8-Oxo-guanine; Oxidative stress; Protein carbonylation; Sirtuin; Superoxide dismutase; Yeast
Online: 24 April 2020 (08:54:52 CEST)
Almond (Prunus dulcis (Mill.) D.A.Webb) is one of the largest nut crops in the world. Recently, phenolic compounds, mostly stored in almond skin, have been associated with much of the health-promoting behavior associated with their intake. The almond skin enriched fraction obtained from cold-pressed oil residues of the endemic Moroccan Beldi ecotypes is particularly rich in chlorogenic acid. In this study, both almond skin extract (AE) and chlorogenic acid (CHL) supplements, similar to traditional positive control resveratrol, significantly increased the replicative life-span of yeast compared to the untreated group. Our results showed that AE and CHL significantly reduced the production of reactive oxygen and nitrogen species (ROS/RNS), most likely due to their ability to maintain mitochondrial function during aging, as indicated by the maintenance of normal mitochondrial membrane potential in treated groups. This may be associated with the observed activation of the anti-oxidative stress response in treated yeast, which results in activation at both gene expression and enzymatic activity levels for SOD2 and SIR2, the latter being an upstream inducer of SOD2 expression. Interestingly, the differential gene expression induction of mitochondrial SOD2 gene at the expense of the cytosolic SOD1 gene confirms the key role of mitochondrial function in this regulation. Furthermore, AE and CHL have contributed to the survival of yeast under UV-C-induced oxidative stress, by reducing the development of ROS / RNS, resulting in a significant reduction in cellular oxidative damage as evidenced by decreased membrane lipid peroxidation, protein carbonyl content and 8-oxo-guanine formation in DNA. Together, these results demonstrate the interest of AE and CHL as new regulators in the replicative life-span and control of the oxidative stress response of yeast.
Subject: Biology, Other Keywords: Mediator: stress; MCHM; Med15; Snf1; polyQ; protein chaperone; master variator; intrinsically disordered regions; yeast; hydrotrope; transcription factors; Myc tag; inorganic phosphate
Online: 3 February 2020 (13:37:07 CET)
The Mediator is composed of multiple subunits conserved from yeast to humans and plays a central role in transcription. The tail components are not required for basal transcription but are required for response to different stresses. While some stresses are familiar such as heat, desiccation, and starvation, others are exotic, yet yeast can elicit a successful stress response. MCHM is a hydrotrope that induces growth arrest in yeast. We found that a naturally occurring variation in the Med15 allele, a component of the Mediator tail, altered the stress response to many chemicals in addition to MCHM. Med15 contains two polyglutamine repeats (polyQ) of variable lengths that change the gene expression of diverse pathways. Med15 protein existed in multiple isoforms and its stability was dependent on Ydj1, a protein chaperone. The protein level of the Med15 with longer polyQ tracts was lower and turned over faster than the allele with shorter polyQ repeats. MCHM sensitivity via variation of Med15 was regulated by Snf1 in a Myc tag dependent manner. Tagging Med15 with Myc altered its function in response to stress. Genetic variation in transcriptional regulators magnifies genetic differences in response to environmental changes. These polymorphic control genes are master variators.
REVIEW | doi:10.20944/preprints202004.0375.v1
Subject: Biology, Other Keywords: bipolar mitotic spindle; fission yeast; kinesin; kinetochore; microtubule dynamics; microtubule polymerase; microtubule–associated proteins (MAPs); spindle pole body (SPB); sister chromatid cohesion
Online: 21 April 2020 (05:58:17 CEST)
The bipolar mitotic spindle drives accurate chromosome segregation by capturing the kinetochore and pulling each set of sister chromatids to the opposite poles. In this review, we describe recent findings on the multiple pathways leading to bipolar spindle formation in fission yeast and discuss these results from a broader perspective. Roles of four mitotic kinesins (Kinesin-5, Kinesin-6, Kinesin-12 and Kinesin-14) in spindle assembly are depicted, and how a group of microtubule-associated proteins, sister chromatid cohesion and the kinetochore collaborates with these motors is shown. We have paid special attention to the molecular pathways that render otherwise essential Kinesin-5 to become non-essential: how cells build bipolar mitotic spindles without the need for Kinesin-5 and where the alternate forces come from are considered. We highlight the force balance for bipolar spindle assembly and explain how outward and inward forces are generated by various ways, in which the proper fine-tuning of microtubule dynamics plays a crucial role. Overall, these new pathways have illuminated remarkable plasticity and adaptability of spindle mechanics. Kinesin molecules are regarded as prospective targets for cancer chemotherapy and many specific inhibitors have been developed. However, several hurdles have arisen against their clinical implementation. This review provides insight into possible strategies to overcome these challenges.