The soil and groundwater of Bhagobangola I block of Murshidabad district, West Bengal, India is severely arsenic contaminated. A bacterium was isolated from the garden soil of Mahishasthali village, which could tolerate 36.49 mM arsenic (III), 280.44 mM arsenic (V) and 63 mM chromium (III), which makes it arsenic (III & V) and chromium (III) hyper-tolerant bacterium. The growth pattern of this bacterium does not show much alteration in presence of 10 mM arsenic (III) and chromium (III), emphasizing its resistance to these heavy metals. Scanning electron microscopy depicted the size of this bacterium to be ~1.45 µm. 16S rDNA sequencing followed by subsequent phylogenetic analysis established the identity of this bacterium as Microbacterium paraoxydans. The bacterium is capable of bioremediation of arsenic and showed 30.8% & 22.6%, and 35.2% and 30.5% of bioremediation over a period of 24 and 48 hours in 1 mM and 4 mM arsenite, respectively. Microbacterium paraoxydans also exhibit plant growth promoting properties like nitrogen fixation, phosphate solubilization, indole-3-acetic acid production and production of siderophores. Therefore, the heavy metal resistance, bioremediation potential and plant growth promoting potential of the bacterium could be utilized not only for reduction of arsenic toxicity in soil and groundwater but also for plant growth promotion by using it as a biofertilizer.

Ralstonia solanacearum is a pathogen that causes bacterial wilt producing severe damage in staple solanaceous crops. Traditional control has low efficacy and/or environmental impact. Recently, the bases of a new biotechnological method by lytic bacteriophages vRsoP-WF2, vRsoP-WM2 and vRsoP-WR2 with specific activity against R. solanacearum were established. However, some aspects remain unknown, such as the survival and maintenance of the lytic activity after submission to a preservation method as the lyophilization. To this end, viability and stability of lyophilized vRsoP-WF2, vRsoP-WM2 and vRsoP-WR2 and their capacity for bacterial wilt biocontrol have been determined against one pathogenic Spanish reference strain of R. solanacearum in susceptible tomato plants in different conditions and making use of various cryoprotectants. The assays carried out have shown satisfactory results with respect to the viability and stability of the bacteriophages after the lyophilization process, maintaining high titres throughout the experimental period, also with respect to the capacity of the bacteriophages for the biological control of bacterial wilt, controlling this disease in more than 50% of the plants. The results offer good prospects for the use of lyophilization as a conservation method for the lytic bacteriophages of R. solanacearum in view of their commercialization as biocontrol agents.

Epidemic diseases that arise from infectious RNA viruses, particularly influenza viruses, pose a constant threat to the global economy and public health. Viral evolution has undermined the efficacy of acquired immunity from vaccines and the antiviral effects of FDA-approved drugs. As such, there is an urgent need to develop new antiviral lead agents. Natural compounds, owing to their historical validation of application and safety, have become a promising solution. In this light, a novel marine bacterium, Pseudomonas sp. M20A4R8, has been found to exhibit significant antiviral activity [half maximal inhibitory concentration (IC50) = 1.3 µg/mL, selectivity index (SI) = 919.4] against influenza virus A/Puerto Rico/8/34, surpassing the activity of chloroquine. The antiviral response by M20A4R8 extract was induced during post-entry stages of the influenza virus, indicating suitability for post-application after the establishment of viral infection. Furthermore, post-treatment with M20A4R8 extract protected the host from virus-induced apoptosis, suggesting its potential use in acute respiratory disease complexes resulting from immune effectors' overstimulation and autophagy-mediated self-apoptosis. The extract demonstrated an outstanding therapeutic index against influenza virus A/Wisconsin/15/2009 (IC50 = 8.1 µg/mL, SI = 146.2) and B/Florida/78/2015 Victoria lineage (IC50 = 3.5 µg/mL, SI = 343.8), indicating a broad anti-influenza virus activity with guaranteed safety and effectiveness. This study provides a new perspective on mechanisms for preventing a broad spectrum of viral infections through antiviral agents from novel and natural origins. Future studies on a single or combined compound from the extract hold promise, encouraging its use in preclinical challenge tests with various influenza virus strains.

The influenza virus has been the primary cause of the pandemic, posing a constant threat to human society. Due to its genetic evolution and continuous outbreak, antiviral research currently focuses on exploring a novel lead agent. A comprehensive antiviral screening discovered a marine bacterium whose extract exerted excellent efficacy against influenza viruses. Parerythrobacter sp. M20A3S10, a novel strain under the family Erythrobacteraceae, could produce carotenoids exhibiting antiviral and anticancer activity by enhancing the cellular immune system. Post-treatment of M20A3S10 extract showed outstanding therapeutic indexes: against influenza virus A/PR8 (H1N1) [selectivity index (SI) = 24.0], A/Wisconsin/15/2009 (H3N2) (SI = 30.1) and B/Florida/78/2015 (SI = 38.2). Comparably, the effectiveness was demonstrated against Zika virus (ZIKV) and dengue virus type 2 (DENV2) with an SI of 22.5 and 24.1, respectively, namely broad-spectrum activity. Of note, the antiviral responses resulted from the common replication mechanism between IAV, ZIKV, and DENV2. The stimulation of apoptosis-mediated cellular immunity prevented the viral release and protected the host, suggesting that switching from necroptosis to apoptosis is a novel antiviral target. Although the specific compound affecting the antiviral activity was not identified, its promising efficacy with broad activity will contribute to developing a strategy for preventing future pandemics.

The antibacterial activities of plant flavonoids have increasingly paid a more attention to. The antimicrobial quantitative structure-activity relationship was established for plant flavonoids against gram-positive bacteria, and its major action site was confirmed as the cell membrane in our previous works. To understand whether there are similar antibacterial modes of plant flavonoids against Gram-negative to -positive bacteria, here the minimum inhibitory concentrations (MICs) of thirty-seven plant flavonoids to Escherichia coli were determined using microdilution broth method, and then the correlation between their lipophilic parameter ACD/LogP or LogD_7.40 values and their MICs were analyzed. Combined with those correlations analyses from forty-six plant flavonoids reported, the results showed that there is significantly correlation between their LogP values and MICs to Gram-negative bacteria. However, it is difficult to predict the MICs of plant flavonoids against gram-negative from their lipophilic parameters like against Gram-positive bacteria. After compared the characters of two regression curves established from plant flavonoids against gram-negative and -positive bacteria, it was further found that the antibacterial activities of most plant flavonoids to Gram-negative bacteria are greater than to Gram-positive bacteria when their LogP values are less than about 3.0, but less than which when their LogP values are more than about 3.6. Moreover, different from mainly acting on the cell membrane of Gram-positive bacteria, the comparison of both two curves proposed that there are multiple action modes of plant flavonoids against Gram-negative bacteria, while among them the cell membrane is also an important action site. Combined the analyses for reported data, it was further suggested that the DNA gyrase is another important target of plant flavonoids against Gram-negative bacteria.

Bifidobacterium is the most beneficial flora of the human gastrointestinal tract, but there is a concentration threshold for Bifidobacterium to exert its beneficial properties. In this work, the effect of several simple culture methods on the number of viable bifidobacteria was discussed to improve its viable concentrations, and we unexpectedly discovered that bifidobacteria have inert growth. The concentration of viable bacteria of two isolated Bifidobacterium animalis subsp. lactis, BZ11 and BZ25 and Lactobacillus plantarum SQ-4 were investigated using solid-liquid-liquid circulation subculture, solid-liquid-liquid subculture and solid-liquid-liquid circulation subculture. These 3 subculture methods increase the viable cell concentration, and the best is the solid-liquid-liquid subculture. The highest concentrations of third-generation BZ11 and BZ25 were 9.62 × 109 CFU/mL and 1.21 × 1010 CFU/mL in order by solid-liquid-liquid subculture method, which was 10.38 times and 42.31 times higher (P<0.05) than those of the first generation, respectively. However, none of these three subculture methods increased the concentration of SQ-4. These results suggested that Bifidobacterium has growth inertia and Solid-liquid-liquid passage culture inhibiting the growth inertia. This finding is valuable in promoting the industrial application of probiotic bifidobacteria to potential probiotic food production.

Plant flavonoids have increasingly paid a close attention to for new antimicrobial agents or adjuvants. In our previous work, it was confirmed that the cell membrane is the major site of plant flavonoids acting on the gram-positive bacteria, and which likely involves the inhibition of the respiratory chain. Inspired by the similar structural and antioxidant characters of plant flavonoids to MKH₂, we deduced that the quinone pool is probably a key target of plant flavonoids inhibiting gram-positive bacteria. To verify this, twelve plant flavonoids with six structural subtypes were preliminary selected, and their MICs against gram-positive bacteria were predicted from the antimicrobial quantitative relationship of plant flavonoids to gram-positive bacteria. The results showed they have different antimicrobial activities. After their MICs against S. aureus were determined using broth microdilution method, nine compounds with the MICs ranged from 2 to 4,096 μg/mL or more than 1,024 μg/mL were eventually selected, and then their MICs against S. aureus were determined interfered with different concentrations of MK-4 and the MKs extracted from S. aureus. The results showed that the greater the antibacterial activities of plant flavonoids were, the more greatly their antibacterial activities decreased along with the increase of the interfering concentrations of MK-4 (from 2 to 256 μg/mL) and MK extract (from 4 to 512 μg/mL), and while those, with the MICs equal to or more than 512 μg/mL, decreased a little or remained unchanged. Especially, under the interference of MK-4 (256 μg/mL) and MK extract (512 μg/mL), the MICs of α-mangostin, a compound with greatest inhibitory activity to S. aureus in these twelve plant flavonoids, increased by 16 times and 8 to16 times, respectively. Based on these above, it was proposed that the quinone pool is a key target of plant flavonoids inhibiting gram-positive bacteria, and which likely involves multiple mechanisms including some enzyme and non-enzyme inhibitions.

The copolyester of 3-hydroxybutyrate (3HB) and 3-hydoxyhexanoate (3HHx), PHBHHx, is a bi-odegradable plastic that has a high flexibility, softness, wide process window and marine bio-degradability. PHBHHx is usually produced from structurally related carbon sources such as vegetable oils or fatty acids but not from inexpensive carbon sources like sugars. In the previous studies, we demonstrated that engineered strains of hydrogen-oxidizing bacterium, Cupriavidus necator synthesized PHBHHx with high cellular content from not only sugars but also from CO2 as the sole carbon source in the flask culture. In this study, highly efficient production of PHBHHx from CO2 was investigated by pH-stat jar cultivation of the recombinant C. necator strains with feeding the substrate gas mixture (H2/O2/CO2=8:1:1) to complete mineral medium in recycled-gas closed-circuit culture system. As the result with the strain MF01/pBPP-ccrMeJAc-emd, the dry cell mass and PHBHHx concentration reached up to 59.62 ± 3.18 g･L-1 and 49.31 ± 3.14 g･L-1, respectively after 212 h of jar cultivation with limited addition of ammonia and phosphate solutions. The 3HHx composition was close to 10 mol% which is suitable for practical applica-tions. It is expected that autotrophic cultivation of the recombinant C. necator can be a feasible process for mass production of PHBHHx from CO2.

Citrus greening disease or huanglongbing (HLB) caused by Candidatus Liberibacter asiaticus (CLas) limits the citrus production worldwide. CLas is transmitted by the Asian citrus psyllid (ACP), Diaphorina citri (Hemiptera: Psyllidae) in a persistent-propagative manner. Application of insecticides to manage the psyllid vectors and disease is the most common practice. Understanding the molecular interaction between CLas and ACP and interrupting the interrelationship can provide an alternative to insecticides for managing citrus greening disease. Transcriptome analysis of ACP in response to CLas showed differential expression of 3911 genes (2196 up-regulated, and 1715 down-regulated) including the key genes of ACP involved in cytoskeleton synthesis and nutrition-related proteins. Majority of the differentially expressed genes were categorized under molecular function followed by cellular components and biological processes. KEGG pathway analysis showed differential regulation of carbohydrate, nucleotide and energy metabolic pathways, the endocytotic pathway and the defense-related pathways. Differential regulation of genes associated with the key pathways might favors CLas to become systemic and propagate in its insect vector. The study provides an understanding of genes involved in circulation of CLas in ACP. The candidate genes involved in key physiological processes and CLas transmission by ACP would be potential targets for sustainable management of ACP and CLas.

Filamentous manganese (Mn) oxide particles, which occur in the suboxic zone of stratified waterbodies, are important drivers of diverse elemental cycles. Although these particles are considered to be bacteriogenic, the environmental factor responsible for their formation has not been identified. Based on this study of laboratory cultures of a model Mn(II)-oxidizing bacterium, the supply of algal extracellular polymeric substances (EPS) was shown to stimulate Mn(II) oxidation and thus the production of filamentous Mn oxide particles. This observation was consistent with results obtained for naturally occurring particles collected from a near-bottom layer (depth of ~90 m) in the northern basin of Lake Biwa, Japan, that is, most Mn particles resembling delta-MnO2 were associated with an EPS-like gelatinous matrix, which contained dead algal cells and was lectin-stainable. In the lake water column, EPS produced by photosynthesis sank to the bottom layer. The analysis of the quality of water samples, which have been collected from the study site for 18 years, reveals that the annual average total phytoplankton biovolume in the surface layer correlates with the density of filamentous Mn particles in the near-bottom layer. Among different phytoplankton species, green algae appeared to be the key species. The results of this study suggest that algal EPS production induces the formation of filamentous Mn oxide particles in the near-bottom layer of the northern basin of Lake Biwa.

The purpose of bovine colostrum, being the milk secreted by a cow after giving birth, is to transfer passive immunity to the calf. The calves have an insufficient immune system as they lack immunoglobulins (Igs). Subsequently, the supply of good quality bovine colostrum is obligatory. The quality of colostrum is classified by low bacterial counts and adequate Ig concentrations. Bacterial contamination can contain a variety of human pathogens or high counts of spoilage bacteria, which becomes more challenging with emerging use of bovine colostrum as food and food supplements. There is also a growing risk for the spread of zoonotic diseases originating from bovines. For this reason, processing based on heat treatment or other feasible techniques are required. This review provides an overview of literature on the microbial quality of bovine colostrum and processing methods to improve its microbial quality and keep its nutritional values as food. The highlights of this review are: high quality colostrum is a valuable raw material in food products and supplements, the microbial safety of bovine colostrum is increased using appropriate processing, suitable effective heat-treatment, which does not destroy the high nutrition value of colostrum, the heat treatment processes are cost-effective compared to other methods, and heat treatment can be performed in both small- and large-scale production

Brevibacillus laterosporus (Bl) is a Gram-positive and spore-forming bacterium belonging to the Brevibacillus brevis phylogenetic cluster. Globally, insect pathogenic strains of the bacterium have been isolated, characterised, and some activities patented. Two isolates, Bl 1821L and Bl 1951, exhibiting pathogenicity against the diamondback moth and mosquitoes, are under development as a biopesticide in New Zealand. However, due to the suspected activity of putative antibacterial proteins (ABPs), the endemic isolates often grow erratically. Various purification methods including size exclusion chromatography, sucrose density gradient centrifugation, polyethylene glycol precipitation, and ammonium sulphate precipitation employed in this study enabled the isolation of two putative antibacterial proteins of ~30 kD and ~48 kD from Bl 1821L and one putative antibacterial protein of ~30 kD from Bl 1951. Purification of the uninduced cultures of Bl 1821L and Bl 1951 also yielded the protein bands of ~30 kD and ~48 kD on SDS-PAGE which indicated their spontaneous induction. Disc diffusion assay was used to determine the antagonistic activities of the putative ABPs. Subsequent transmission electron microscope (TEM) examination of purified putative antibacterial protein-containing solution showed the presence of encapsulin (~30 kD) and polysheath (~48 kD) like structures. Although only the ~30 kD protein was purified from Bl 1951, both structures were seen in this strain under TEM. Furthermore, while assessing the antibacterial activity of some fractions of Bl 1951 against Bl 1821L in size exclusion chromatography method, population of Bl 1821L persister cells was noted. Overall, this work added a wealth of knowledge for the purification of the HMW proteins (bacteriocins) of the Gram-positive bacteria including Bl.

Reproductively lethal mutations (RLMs) are mutations that, upon expression of the encoded lethal phenotypes, cause individuals carrying them to die or to be sterile. An underappreciated fact is that loss-of-function RLMs in protein-coding genes can be phenotypically shielded by favorable environments rendering these genes conditionally non-essential, or by their sister alleles in diploid organisms. Absent of rigorous mitigation, such phenotype-shielding causes the number of genes incurring RLMs to increase over time, and simultaneously allows each RLM to reach high allele frequencies in a conspecific population. Over-accumulation of RLMs then sets the population up for eventual concurrent expression of large numbers of RLMs, and massive deaths in rapid succession, possibly even population-level extinction. This hypothetical scenario in turn predicts that organismal lineages that evolved means to minimize the allele frequencies of phenotypically shielded RLMs are favored by natural selection. We argue that bottlenecking the genome copies destined for reproduction is a universal strategy adopted by all living beings to compel phenotype-based RLM purging. We further postulate that primitive RNA replicons must first evolve bottlenecked reproduction before evolving the capacity to encode diffusible products. In more complex, multicellular organisms, RLM management through bottlenecked reproduction gains additional reinforcement through sexual reproduction. In short, the evidence chronicled in this essay strongly suggest that the Bottleneck, Isolate, Amplify, Select (BIAS) principle, originally proposed to explain intracellular evolutionary dynamics of viruses, may be universally applicable to all living beings.