Search

BACKGROUND: Glyoxal has been implicated as a significant contributor to the formation of secondary organic aerosols, which play a key role in our ability to estimate the impact of aerosols on climate. Elevated concentrations of glyoxal over open ocean waters suggest that there exists an additional source, different from urban and forest environments, which has yet to be identified. METHODS: Based on mass spectrometric analyses of nascent sea spray aerosols (SSAs) and gas-phase molecules generated during the course of a controlled algal bloom, the work herein suggests that marine microorganisms are capable of excreting toluene in response to environmental stimuli. Additional culture flask experiments demonstrated that pathogenic attack could also serve as a trigger for toluene formation. Using solid-phase microextraction methods, the comparison of samples collected up-channel and over the breaking wave suggests it was transferred across the air-water interface primarily through SSA formation. RESULTS: The presence and then absence of phenylacetic acid in the SSA days prior to the appearance of toluene support previous reports that proposed toluene is produced as a metabolite of phenylalanine through the Shikimate pathway. As a result, once in the atmosphere, toluene is susceptible to oxidation and subsequent degradation into glyoxal. CONCLUSIONS: This work adds to a minimal collection of literature that addresses the primary production of aromatic hydrocarbons from marine microorganisms and provides a potential missing source of glyoxal that should be considered when accounting for its origins in remote ocean regions.

The production and development of bioplastics are necessary to solve the crisis originating from the accumulation of non-biodegradable plastics in the environment. This study aimed to synthesize polyhydroxybutyrate (PHB) using orange wastes by the bacterium separated from the Caspian Sea. Seven PHB synthesizing bacterial isolate were isolated from Caspian Sea water. The initial screening for PHB synthesis was performed with a dye-based method. The most powerful marine bacterium with the synthesis of 1.73 g/L PHB was identified via 16S rRNA gene sequencing as Bacillus sp. Caspian04 and its nucleotide sequence was preserved with the accession number OR999904.1 in GeneBank. PHB synthesis increased in the presence of ammonium chloride, 4% orange wastes extract, and 3% NaCl, at temperature of 35 °C and pH 8.0. Using the orange wastes extract (4% w/v) led to the synthesis of 5.22 g/L PHB, which can help reduce the cost of PHB synthesis. FTIR, 1H NMR, 13C NMR, XRD, and TGA were used to evaluate extracted PHB's characterization. The present study is the first attempt to bioplastic synthesis by bacteria isolated from the Caspian Sea. Furthermore, with the biotechnological production of PHB from orange wastes by Bacillus sp. Caspian04, the way will be paved for the development of management strategy of solid wastes and highlights the role of marine bacteria in the production of polymers with commercial value. [ABSTRACT FROM AUTHOR]

This study investigated the use of native microbiota from the sugar kelp Saccharina latissima in the form of fermented kelp fluid (FKF) from a spontaneous anaerobic fermentation process as a starter culture (SC) for the fermentation of freshly harvested biomass of the same species. Rapid (<48 h) acidification (pH < 4.3) was achieved for S. latissima inoculated with FKF, at a fermentation temperature of 21°C. Kelp inoculated with a commercial strain of Lactiplantibacillus plantarum (Lp , positive control) reached a similar pH level after 5 days, while kelp with no SC (negative control) did not reach a pH level below 4.3 within 9 days. The microbiota of the FKF-SC as well as the FKF-inoculated S. latissima samples was dominated by lactic acid bacteria (LAB) identified as L. plantarum. The SC in these samples successfully converted mannitol into lactic acid as the main fermentation product. In contrast, a higher production of acetic acid and ethanol was measured in the negative control samples than in other groups; this reflects a different microbial profile, including marine bacteria which could not be identified by MALDI-TOF biotyping. Challenge trials of S. latissima samples from experimental and commercial fermentation processes with Bacillus cereus did not result in the growth of this food pathogen, even at pH levels within a viable range for this species (pH > 4.3). These preliminary results provide a foundation for further isolation of suitable SCs for kelp fermentation in commercial production and for assessing the food safety of fermented kelp. Efficient and safe fermentation processes will increase sustainability in kelp production and enable a broader use of kelp ingredients in food applications. [ABSTRACT FROM AUTHOR]

Shewanella is a genus of Gram-negative marine bacteria with some species associated with human and shellfish illnesses. This study evaluated the abundance of Shewanella species in oysters and seawater from the Chesapeake and Maryland Coastal Bays at four sites between 2019 and 2021. Physicochemical parameters such as temperature, salinity, dissolved oxygen, turbidity, pH, chlorophyll-a, rainfall within the last 48 h, total dissolved solids, and atmospheric pressure were also recorded to evaluate if there was a correlation between environmental parameters and the level of Shewanella. The highest total Shewanella counts were 1.8 × 107 CFU/g in oysters and 4.0 × 102 CFU/mL in seawater. 16S rRNA sequencing was performed on 1,344 representative isolates of which 890 (713 oyster, 177 seawater) were confirmed as Shewanella within 16 species. The top four species isolated from oysters and seawater were S. khirikhana a known shrimp pathogen (49%), S. marisflavi (19%), S. loihica (11%), and S. algae (8%). Testing for alpha and beta hemolysis were performed on all confirmed Shewanella isolates. Beta hemolysis was observed in 405 (46%) of the isolates of which 313 were in oysters and 92 in seawater. In oysters, beta-hemolysis was most prevalent in S. khirikhana (233 of 344 isolates, 68%), while in seawater 64 of 92 isolates (70%) were beta-hemolytic strains. Beta-hemolysis suggests that these could be potentially pathogenic strains. Correlations were performed between physicochemical attributes of the seawater and Shewanella counts. Only seawater temperature and dissolved oxygen correlated with Shewanella counts (r = 0.45 and − 0.41), respectively. No correlations were observed between the physicochemical parameters and Shewanella abundances in oysters. Results suggest that virulent strains of Shewanella may be present in oysters and seawater from the Chesapeake and Maryland Coastal Bays, perhaps as a consequence of rising seawater temperatures. [ABSTRACT FROM AUTHOR]

Background: The marine Gram-negative bacterium Vibrio anguillarum is one of the major pathogens in aquaculture. Iron uptake is a prerequisite for virulence and is strictly controlled by a global iron uptake regulator, Fur, which acts as a repressor under iron-replete conditions. When iron is depleted, Fur also functions as an activator, playing an important role in pathogenesis. It is unclear whether this upregulation model is mediated by a small RNA, RyhB. Methods: The small RNA, VaryhB , was deleted in V. anguillarum strain 775, and its regulon was investigated using transcriptomic analysis. The roles of VaRyhB in siderophore synthesis, chemotaxis and motility, and oxidative stress were evaluated using chrome azurol S (CAS) liquid assay, swimming motility assay, and intracellular reactive oxygen species (ROS) assay, respectively. The virulence of VaRyhB was evaluated by challenging turbot larvae intraperitoneally. Results: The small RNA called VaRyhB identified in V. anguillarum strain 775 is significantly longer than that in Escherichia coli. Transcriptomic analysis revealed that VaRyhB is critical for iron homeostasis under limited iron conditions, and deletion of VaRyhB resulted in lower expression levels of certain genes for siderophore biosynthesis and transport, thereby leading to impaired growth, reduced siderophore production, and decreased pathogenesis. The virulence factor motility is also upregulated by VaRyhB, and reduced motility capability was observed in the ΔVaryhB mutant, which may be another reason resulting in weak pathogenesis. The sensitivity toward H2O2 in the ΔVafur mutant could be restored by the loss of VaRyhB, suggesting that the role of Fur in oxidative stress is mediated by VaRyhB. VaRyhB also functions to inhibit the expression of genes involved in Fe-S assembly and the TCA cycle. In addition, two aspects of the type VI secretion system and molybdenum cofactor biosynthesis were first identified as being regulated by VaRyhB. Conclusion: In V. anguillarum , the sRNA VaRyhB plays a critical role in the inhibition of genes involved in the TCA cycle, Fe-S assembly, and the type VI secretion system. It is also essential for the activation of siderophore synthesis, chemotaxis and motility, and anaerobic denitrification. Our work provides the first evidence of the VaRyhB regulon and its role in the pathogenesis of V. anguillarum. [ABSTRACT FROM AUTHOR]

There is still much to be learned about the properties of siderophores and their applications. This study was designed to characterize and optimize the production of the siderophore produced by a marine bacterium Pseudomonas sp. strain ASA235 and then evaluate their use in bioleaching of rare earth elements (REEs) from spent Nickel–metal hydride (NiMH) batteries. The results of both Tetrazolium and Arnowʼs tests indicated that the test organism produces a mixed-type siderophore of pyoverdine family, a result that was confirmed by FT-IR and MALDI-TOFF analyses. Optimization of pH, temperature, incubation period, and iron concentration for siderophore production led to a noticeable shift from 44.5% up to 91% siderophore unit when the test bacterium was incubated at 28 °C and pH 7 after 72 h in the absence of iron. The purified siderophore showed the ability to bleach about 14.8% of lanthanum from the anode of the NiMH battery along with other elements, although in lower amounts. This data put siderophores in distinct focus for further prospective studies intending the bioleaching of such precious elements. The scaling up of this process and optimization would make a big difference in such a green bioleaching strategy, allowing us to recover such precious elements in an environmentally friendly way. [ABSTRACT FROM AUTHOR]

Marine resources are attractive for screening new useful bacteria. From a marine sediment sample, we performed isolation and screening of bacterial strains in search of new bioactive compounds. HPLC and ESI-MS analysis indicated that the new bacterium, Lysinibacillus sp. CTST325 (NBRC 116944), produced a new peptidic compound, lysinibacin. Genome sequence analysis of Lysinibacillus sp. CTST325 indicated the presence of several biosynthetic gene clusters for secondary metabolites, including lanthipeptides. The structure determination of lysinibacin was performed using CID-MS and NMR spectral data. As a result, lysinibacin was identified as a new class III lanthipeptide, containing N-dimethylated Tyr at the N-terminus and the unusual amino acid labionin at the C-terminus. The biosynthetic gene cluster of lysinibacin was identified from the genome data of the strain CTST325, based on the structure of lysinibacin. Lysinibacin showed antibacterial activity against Gram-positive bacteria. [ABSTRACT FROM AUTHOR]

AbstractMicrobial xylanases are xylan hydrolyzing enzymes which has congregated attention due to their immense potential in many industries. The current study is focused on xylanase from bacterial isolate identified as Bacillus sp. NIORKP76 on an inexpensive agro-industrial waste (wheat bran) under solid-state fermentation. The isolate showed maximum xylanase production in growth medium supplemented with phosphate, NaCl and NH4Cl at 64 mM, 15 mg/mL and 0.3 mg/mL respectively which was maintained at 1:3 substrate to moisture ratio (w/v). Using optimized conditions, the maximum xylanase production in wheat bran was achieved in 72 h at room temperature 28 ± 2 °C. Xylanase exhibited pH optimum of 8.0 and retained 92% of its residual activity after 24 h incubation at pH 8. Xylanase displayed optimum activity at 60 °C, whereas it remained unhindered even after 12 h of incubation period at 30 and 40 °C. The xylanase isolated in this study was purified to homogeneity with a molecular weight of approximately 28 kDa. Xylanase from Bacillus sp. NIORKP76 was potentially converting agro-residues into biofuel feedstock. Pretreated wheat bran produced the highest yield fermentable sugars (141 mg/g), after 8 h incubation with 5 U/g xylanase and at 40 °C. [ABSTRACT FROM AUTHOR]

Xylanase and cellulase derived from Bacillus sp. NIORKK2 and Bacillus sp. NIORKK7 were used to saccharify hot water-pretreated biomass, leading to a greater release of total reducing sugars (TRS) compared to untreated biomass. Optimized enzyme cocktails containing both xylanase and cellulase proved more effective in TRS release than individual enzymes. For Bacillus sp. NIORKK2, xylanase showed optimal activity at a temperature of 55 °C, pH 7, with a 20-min (minute) incubation, while for Bacillus sp. NIORKK7, cellulase showed optimal activity at 65 °C, pH 7, with a 60-min incubation. Among tested lignocellulosic biomasses, hot water-pretreated wheat bran yielded 478.046 mg/g of TRS with the enzyme cocktail. This yield surpassed the TRS releases achieved when individual enzymes were applied separately. The study demonstrates the efficient saccharification of agricultural waste, specifically mango leaves, which are abundant in states like Goa, producing 579 mg of TRS per gram with an enzyme cocktail concentration of 0.5 U/mg, resulting in an 87% saccharification. This study represents the inaugural demonstration of efficient saccharification of mango leaves, leveraging marine bacterial xylanase and cellulase cocktails. This breakthrough highlights the innovative potential for utilizing these enzymes to unlock bioethanol production from agrarian residues, marking a significant advancement in renewable energy research. [ABSTRACT FROM AUTHOR]

Animal holobionts constitute diverse yet interconnected landscapes of microenvironments that harbor specific bacterial communities with distinct functions. An increasing body of literature suggests a partitioning and distinct functional profiles of bacterial communities across shark microenvironments, which has led to the proposition that beneficial bacterial functions may contribute to shark health. Here, we provide a first assessment of bacterial communities in different microenvironments of black-tip reef sharks (Carcharhinus melanopterus), the most abundant reef shark species across the Indo-West Pacific. Collecting samples from 34 sharks from the Amirante Islands, Seychelles, we characterized the corresponding bacterial communities of two external skin locations, within the buccal cavity, and of the cloaca (representing the gut microbiome) using 16S rRNA gene amplicon sequencing. Overall, shark-associated bacterial communities were distinct from seawater, and skin, buccal, and cloaca samples were distinct from each other. Shark cloaca samples and seawater exhibited lower bacterial alpha diversity and richness compared to the other microenvironments. Predicted functional profiles and Linear Discriminant Effect Size analysis suggest potential differences in metabolic pathways present in the different shark-associated bacterial communities and in the seawater. Taxonomy-based functional inference suggests cloaca-associated bacterial communities specialize in the consumption and breakdown of various food items. Taken together, our data suggest distinct bacterial niche habitats within the 'microbial landscape' of black-tip reef sharks, as indicated by distinct bacterial communities and their predicted metabolic functions. Future (meta)genomic and functional work will help reveal potential roles of bacteria in the health of their shark hosts. [ABSTRACT FROM AUTHOR]

Alginate lyases have the potential to be used as a therapeutic agent for P. aeruginosa infections. The present work was focused on the characterization of free and immobilized alginate lyase produced by marine bacteria, Enterobacter tabaci RAU2C isolated previously in the laboratory for alginate lyase production and exploring the potential of alginate lyase as an anti-biofilm agent against the P. aeruginosa biofilm. RAU2C alginate lyase was immobilized using an epoxy-activated curdlan matrix by three different methods. Further, the free and immobilized were characterized for its optimal pH and temperature. The effect of alginate concentration on alginate lyase activity was assessed and the kinetic parameters were evaluated. The anti-biofilm activity of the crude alginate lyase was studied using biofilm inhibition and disruption assays in microtiter plates with crystal violet. The biofilm disruption by RAU2C alginate lyase was also ascertained by microscopic analysis. The immobilization matrix prepared using method 3 had a better binding capacity compared to other methods. Both soluble and immobilized alginate lyase exhibited optimal activity at 37 °C and pH 7.0. Km and Vmax of soluble and immobilized alginate lyase were found to be 3.38 mg/mL, 22.98 mg/mL min and 3.67 mg/mL and 26.59 mg/mL min respectively. Both microtiter assay and microscopic analysis confirmed the prevention and dispersal of pre-existing biofilms by crude RAU2C alginate lyase, highlighting its potential as an anti-biofilm agent against P. aeruginosa. The study highlights the efficacy of RAU2C alginate lyase as an anti-biofilm agent in controlling P. aeruginosa biofilms. [ABSTRACT FROM AUTHOR]

Background: Vibrio parahaemolyticus is a marine bacterium causing seafood-associated gastrointestinal illness in humans and acute hepatopancreatic necrosis disease (AHPND) in shrimp. Bacteriophages have emerged as promising biocontrol agents against V. parahaemolyticus. This study characterizes Vibrio phage VPK8, focusing on host specificity, efficiency of plating (EOP) variability across V. parahaemolyticus isolates from diverse sources and other Vibrio species, morphology, genomic features, and bacteriolytic potential. Methods: Vibrio phage VPK8 was isolated from blood cockles in Thailand using a mixed-host approach and purified via the double-layer agar method. Host specificity was evaluated using spot assays and EOP measurements against 120 Vibrio strains, including AHPND-associated, clinical, and seafood isolates. Phage morphology was characterized by transmission electron microscopy (TEM), while genomic features were analyzed using next-generation sequencing. Lytic characteristics, including latent period and burst size, were determined through one-step growth curves, and bacterial growth reduction was evaluated over a 24-h. Results: Vibrio phage VPK8 is a lytic phage with a 42,866 bp linear double-stranded genome, G + C content of 49.4%, and 48 coding sequences. Phylogenetic analysis grouped it within the Autographiviridae family, showing 95.96% similarity to Vibrio phage vB_VpaP_MGD1. Viral proteomic analysis placed VPK8 within the Pseudomonadota host group. Spot assays indicated broad lytic activity, but EOP analysis revealed high infectivity in clinical and seafood V. parahaemolyticus isolates, as well as some V. cholerae and V. mimicus strains. TEM revealed an icosahedral head (~ 60 nm) and a short tail. At a multiplicity of infection of 0.01, VPK8 exhibited a latent period of 25 min, a burst size of 115, and effectively inhibited the reference host V. parahaemolyticus PSU5124 within 6 h, maintaining its lytic activity and stability for over 24 h. Conclusions: This study provides a detailed characterization of Vibrio phage VPK8 which exhibits targeted infectivity with high EOP in clinical and seafood V. parahaemolyticus isolates, as well as selected Vibrio species. Its stable lytic performance, rapid replication, and genomic safety suggest its potential for phage-based applications. Further studies should explore its in vivo efficacy and the genetic features contributing to phage resistance mechanisms, enhancing its potential applicability in managing Vibrio-related diseases. [ABSTRACT FROM AUTHOR]

Chemical communication between marine bacteria and their algal hosts drives population dynamics and ultimately determines the fate of major biogeochemical cycles in the ocean. To gain deeper insights into this small molecule exchange, we screened niche-specific metabolites as potential modulators of the secondary metabolome of the roseobacter, Roseovarius tolerans. Metabolomic analysis led to the identification of a group of cryptic lipids that we have termed roseoceramides. The roseoceramides are elicited by iron-binding algal flavonoids, which are produced by macroalgae that Roseovarius species associate with. Investigations into the mechanism of elicitation show that iron limitation in R. tolerans initiates a stress response that results in lowered oxidative phosphorylation, increased import and catabolism of algal exudates, and reconfiguration of lipid ynthesis to prioritize production of roseoceramides over phospholipids, likely to fortify membrane integrity as well as promote a sessile and symbiotic lifestyle. Our findings add new small molecule words and their "meanings" to the algal-bacterial lexicon and have implications for the initiation of these interactions. [ABSTRACT FROM AUTHOR]

The rise of bacterial infections and increasing antibiotic resistance underscores an urgent need for new, effective antimicrobial agents with marine bacteria offering a unique and promising source for novel antibiotic compounds to combat persistent and emerging pathogens. In this research, five compounds were achieved from marine Streptomyces sp., C2-13, and their yield was enhanced with the addition of zinc sulfate at 0.5 mM. All compounds have been evaluated for their antibacterial activity against multiple pathogens, among which good activity was achieved against S. aureus , while potent activity was achieved against Riemerella anatipestifer with its IC50 value at 200 µm and bactericidal effect at 300 µm. Among all compounds, 4 was more active against both pathogens. A transcriptome analysis of active compound 4 showed its antibacterial effect on R. anatipestifer by inhibiting 30S and 50S ribosomal subunits, resistance mechanisms, and gliding motility proteins IX secretion system (T9SS) and interfering with protein translations process, secretion system, defense and resistance mechanisms, ultimately resulting in effective inhibition of normal bacterial growth and its motility. To investigate the anti-bacterial mechanism, all compounds were docked with two enzymes and TLR4 protein for predicting the vaccine construct, and the best docking score was achieved against RMFP with the highest score of -12.9 for compound 4. In silico cloning was carried out to ensure the expression of proteins generated and were cloned using E. coli as a host. The simulation studies have shown that both compound 4–RMFP and TLR4–RMFP complex are stable with the system. To the best of our knowledge, this is the first study investigating marine bacterial metabolites against R. anatipestifer with their anti-bacterial mechanism and enhancing their yield through the addition of zinc sulfate ions. [ABSTRACT FROM AUTHOR]

Chemotaxis enables marine bacteria to increase encounters with phytoplankton cells by reducing their search times, provided that bacteria detect noisy chemical gradients around phytoplankton. Gradient detection depends on bacterial phenotypes and phytoplankton size: large phytoplankton produce spatially extended but shallow gradients, whereas small phytoplankton produce steeper but spatially more confined gradients. To date, it has remained unclear how phytoplankton size and bacterial swimming speed affect bacteria's gradient detection ability and search times for phytoplankton. Here, we compute an upper bound on the increase in bacterial encounter rate with phytoplankton due to chemotaxis over random motility alone. We find that chemotaxis can substantially decrease search times for small phytoplankton, but this advantage is highly sensitive to variations in bacterial phenotypes or phytoplankton leakage rates. By contrast, chemotaxis toward large phytoplankton cells reduces the search time more modestly, but this benefit is more robust to variations in search or environmental parameters. Applying our findings to marine phytoplankton communities, we find that, in productive waters, chemotaxis toward phytoplankton smaller than 2 μm provides little to no benefit, but can decrease average search times for large phytoplankton (~20 μm) from 2 wk to 2 d, an advantage that is robust to variations and favors bacteria with higher swimming speeds. By contrast, in oligotrophic waters, chemotaxis can reduce search times for picophytoplankton (~1 μm) up to 10-fold, from a week to half a day, but only for bacteria with low swimming speeds and long sensory timescales. This asymmetry may promote the coexistence of diverse search phenotypes in marine bacterial populations. [ABSTRACT FROM AUTHOR]

L-asparaginase (ASNase) hydrolyzes L-asparagine to L-aspartic acid and ammonia and has been used as an antitumor agent for the treatment of acute lymphoblastic leukemia. ASNase has also been used to mitigate the suspected carcinogenic effects of acrylamide in foods. Commercial ASNases currently used in the pharmaceutical and food industries are produced by microorganisms, such as bacteria and fungi. However, their toxicity and poor thermal stability limit their application. Therefore, identifying novel sources of ASNase is critical. In the present study, we identified an asparaginase-producing marine bacterial strain, GH-W2b, as a Pseudomonas species. Based on the plate assay results, GH-W2b produced ASNase with marginal L-glutaminase (GLNase) activity, which has been reported to cause adverse effects in clinical ASNases. The ASNase activity of GH-W2b was maximized at 50–65 °C and pH 7.0–8.5. Notably, the activities were consistent at a wide range of NaCl concentrations (0–15%) at 37 °C. In addition, compared to the control (no pre-incubation), ASNase activities were retained (>87%) by 2 h pre-incubation at 4–37 °C. Overall, our results suggest that GH-W2b ASNase has the potential to serve as a candidate for the development of salt-tolerant and/or alternative ASNases in pharmaceutical and food products. [ABSTRACT FROM AUTHOR]

The structural diversity of marine natural products is considered a potential resource for the pharmaceutical industry. In our study of marine-derived compounds, one bacterium Bacillus licheniformis S-1 was discovered to have the ability to produce bioactive natural products. After a further chemistry investigation, one novel 4-aminopyridinium derivative, 4-(dimethylamino)-1-(2S-((4hydroxybenzoyl)oxy)propyl)pyridin-1-ium (1), along with 15 known cyclic dipeptides (2–16) were isolated from the bacterium B. licheniformis S-1 derived from a shallow sea sediment. The structures of compounds 1–16 were elucidated through comprehensive NMR spectroscopic and specific optical rotation (OR) data analyses. Compound 6 showed antibacterial activity against Pseudomonas fulva with an MIC value of 50 µg/mL. This is the first study to discover a pyridinium derivative and cyclic dipeptides from B. licheniformis. [ABSTRACT FROM AUTHOR]

Symbiotic marine bacteria that are transmitted through the environment are susceptible to abiotic factors (salinity, temperature, physical barriers) that can influence their ability to colonize their specific hosts. Given that many symbioses are driven by host specificity, environmentally transmitted symbionts are more susceptible to extrinsic factors depending on conditions over space and time. In order to determine whether the population structure of environmentally transmitted symbionts reflects host specificity or biogeography, we analysed the genetic structure of Sepiola atlantica (Cephalopoda: Sepiolidae) and their Vibrio symbionts (V. fischeri and V. logei) in four Galician Rías (Spain). This geographical location is characterized by a jagged coastline with a deep‐sea entrance into the land, ideal for testing whether such population barriers exist due to genetic isolation. We used haplotype estimates combined with nested clade analysis to determine the genetic relatedness for both S. atlantica and Vibrio bacteria. Analyses of molecular variance (AMOVA) were used to estimate variation within and between populations for both host and symbiont genetic data. Our analyses reveal a low percentage of variation among and between host populations, suggesting that these populations are panmictic. In contrast, Vibrio symbiont populations show certain degree of genetic structure, demonstrating that the hydrology of the rías is driving bacterial distribution (and not host specificity). Thus, for environmentally transmitted symbioses such as the sepiolid squid‐Vibrio association, abiotic factors can be a major selective force for determining population structure for one of the partners. [ABSTRACT FROM AUTHOR]

Microbial impacts on early carbonate diagenesis, particularly the formation of Mg-carbonates at low temperatures, have long eluded scientists. Our breakthrough laboratory experiments with two species of halophilic aerobic bacteria and marine carbonate grains reveal that these bacteria created a distinctive protodolomite (disordered dolomite) rim around the grains. Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) confirmed the protodolomite formation, while solid-state nuclear magnetic resonance (NMR) revealed bacterial interactions with carboxylated organic matter, such as extracellular polymeric substances (EPS). We observed a significant carbon isotope fractionation (average δ13C = 11.3‰) and notable changes in Mg/Ca ratios throughout the experiments. Initial medium δ13C was − 18‰, sterile sediments were at 2‰ (n = 12), bacterial-altered sediments were − 6.8‰ (n = 12), and final medium δ13C was − 4.7‰. These results highlight the role of bacteria in driving organic carbon sequestration into Mg-rich carbonates and demonstrate the utility of NMR as a tool for detecting microbial biosignatures. This has significant implications for understanding carbonate diagenesis (dissolution and reprecipitation), climate science, and extraterrestrial research. [ABSTRACT FROM AUTHOR]

This study aimed to enhance the extracellular polymeric substances (EPS) production of Virgibacillus dokdonensis VITP14 and explore its antioxidant potential. EPS and biomass production by VITP14 strain were studied under different culture parameters and media compositions using one factor at a time method. Among different nutrient sources, glucose and peptone were identified as suitable carbon and nitrogen sources. Furthermore, the maximum EPS production was observed at 5% of inoculum size, 5 g/L of NaCl, and 96 h of fermentation. Response surface methodology was employed to augment EPS production and investigate the optimal levels of nutrient sources with their interaction. The strain was observed to produce actual maximum EPS of about 26.4 g/L for finalized optimum medium containing glucose 20 g/L, peptone 10 g/L, and NaCl 50 g/L while the predicted maximum EPS was 26.5 g/L. There was a nine fold increase in EPS production after optimization study. Additionally, EPS has exhibited significant scavenging, reducing, and chelating potential (>85%) at their higher concentration. This study imparts valuable insights into optimizing moderately halophilic bacterial EPS production and evaluating its natural antioxidant properties. According to findings, V. dokdonensis VITP14 was a promising isolate that will provide significant benefits to biopolymer producing industries. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Some marine and extremophilic microorganisms are capable of synthesizing sulfated polysaccharides with a unique structure. A number of studies indicate significant biological properties of individual sulfated polysaccharides, such as antiproliferative activity, which makes them a promising area for further research. In this study, the capsular polysaccharide (CPS) was obtained from the bacterium Cobetia marina KMM 1449, isolated from a marine sediment sample collected along the shore of the Sea of Japan. The CPS was isolated by saline solution, purified by a series of chromatographic procedures, and studied by chemical methods along with 1D and 2D 1H and 13C NMR spectroscopy. The following new structure of the CPS from C. marina KMM 1449 was established and consisted of sulfated and simultaneously phosphorylated disaccharide repeating units: →4)-α-L-Rhap2S-(1→3)-β-D-Manp6PGro-(1→. To elucidate the genetic basis of the CPS biosynthesis, the whole genomic sequence of C. marina KMM 1449 was obtained. The CPS biosynthetic gene cluster (BGC) of about 70 genes composes four regions encoding nucleotide sugar biosynthesis (dTDP-Rha and GDP-Man), assembly (GTs genes), translocation (ABC transporter genes), sulfation (PAPS biosynthesis and sulfotransferase genes) and lipid carrier biosynthesis (wcb operon). Comparative analysis of the CPS BGCs from available Cobetia genomes showed the presence of KMM 1449-like CPS BGC among strains of all three Cobetia species. The study of new natural sulfated polysaccharides, as well as the elucidation of the pathways of their biosynthesis, provides the basis for the development of potential anticancer drugs. [ABSTRACT FROM AUTHOR]

Unique and varied bioactive compounds produced by the ocean have drawn attention and served as a focus for creating antibacterial and anti-inflammatory agents. As part of the approach for locating these research sources, databases such as PubMed, Science Direct, MDPI, Google Scholar, Springer Link, Web of Science, Scopus, and Wiley Online Library were used to identify completed studies. Numerous intriguing bioactive compounds have so far been isolated from marine bacteria. A crucial resource in the ongoing search for novel peptides, proteins, lipids, nucleosides, enzymes, alkaloids, polyketides, and terpenoids is the diversity of marine bacterium strains. This review summarizes several bacterial intracellular and extracellular bioactive compounds that have been applied as antibacterial and anti-inflammatory agents in 2016–2024, which we present in the form of structures, species sources, and evaluations of these compounds' antibacterial and anti-inflammatory activities. Therefore, this review article can be used as a recommendation for utilizing biomaterials from marine bacteria that are promising in the future for industrial-scale production of antibacterial and anti-inflammatory agents.

Abstract Background Reciprocal exchanges of metabolites between phytoplankton and bacteria influence the fitness of these microorganisms which ultimately shapes the productivity of marine ecosystems. Recent evidence suggests that plant growth-promoting hormones may be key metabolites within mutualistic phytoplankton-bacteria partnerships, but very little is known about the diversity of plant growth-promoting hormones produced by marine bacteria and their specific effects on phytoplankton growth. Here, we aimed to investigate the capacity of marine bacteria to produce 7 plant growth-promoting hormones and the effects of these hormones on Actinocyclus sp. growth. Results We examined the plant growth-promoting hormone synthesis capabilities of 14 bacterial strains that enhance the growth of the common diatom Actinocyclus. Plant growth-promoting hormone biosynthesis was ubiquitous among the bacteria tested. Indeed all 14 strains displayed the genomic potential to synthesise multiple hormones, and mass-spectrometry confirmed that each strain produced at least 6 out of the 7 tested plant growth-promoting hormones. Some of the plant growth-promoting hormones identified here, such as brassinolide and trans-zeatin, have never been reported in marine microorganisms. Importantly, all strains produced the hormone indole-3 acetic acid (IAA) in high concentrations and released it into their surroundings. Furthermore, indole-3 acetic acid extracellular concentrations were positively correlated with the ability of each strain to promote Actinocyclus growth. When inoculated with axenic Actinocyclus cultures, only indole-3 acetic acid and gibberellic acid enhanced the growth of the diatom, with cultures exposed to indole-3 acetic acid exhibiting a two-fold increase in cell numbers. Conclusion Our results reveal that marine bacteria produce a much broader range of plant growth-promoting hormones than previously suspected and that some of these compounds enhance the growth of a marine diatom. These findings suggest plant growth-promoting hormones play a large role in microbial communication and broaden our knowledge of their fuctions in the marine environment. Video Abstract

AbstractThis study aimed to evaluate the calcium carbonate precipitation potential of culturable bacteria found in sea surface water. Ureolytic strains were selected using Stuart’s broth. In the preliminary screening, strain DP30 was selected and used in further experiments. Based on the morphological, physiological, and biochemical characteristics with phylogenetic analysis of the 16S rRNA sequencing, the selected strain was identified as Stenotrophomonas maltophilia. DP30 showed the highest urease activity on the 7th day at 28 °C. In addition, it was found that the isolate can show urease activity in low pH environmental conditions such as pH 5. The strain DP30 precipitated CaCO3 on solid Urea-CaCl2 and B4 media but exhibited different crystal morphologies. Plate-like crystals appeared on solid Urea-CaCl2 media, while the strain produced dihydrate calcium oxalate and rhombohedral crystals on solid B4 media. EDS analysis confirmed that the precipitated minerals were composed solely of calcium, carbon, and oxygen. Furthermore, the study showed that S. maltophilia strain DP30 was able to precipitate calcium carbonate under aerobic conditions without urea hydrolysis. These findings suggest that the DP30 strain may have the potential for use in self-healing concrete applications. Moreover, calcium carbonate precipitation without urea hydrolysis where ammonia is produced will provide an environmentally friendly application. [ABSTRACT FROM AUTHOR]

Alginate lyases can fully degrade alginate into various size-defined unsaturated oligosaccharide products by β -elimination. Here, we identified the bifunctional endolytic alginate lyase Aly35 from the marine bacterium Vibrio sp. Strain H204. The enzyme Aly35 is classified into the polysaccharide lyase 7 superfamily and contains two alginate lyase catalytic domains. The relationship and function of the two lyase domains are not well known. Thus, the full-length recombinant enzyme and its truncated proteins Aly35-CD1 (catalytic domain 1), Aly35-CD2 (catalytic domain 2 domain) were constructed. The three enzymes showed similar biochemical characteristics and exhibited temperature and pH stability. Further research showed that Aly35 and Aly35-CD2 can efficiently degrade alginate, polymannuronate (PM) and polyguluronate (PG) into a series of unsaturated oligosaccharides, while Aly35-CD1 exhibits greater PM-degrading activity than that of Aly35-CD2 but can not degraded PG efficiently. The results suggest that the domain (Trp295-His582) is critical for PG-degrading activity, the domain has (Leu53-Lys286) higher PM-degrading activity, both catalytic domains together confer increased alginate (including M-blocks and G blocks)-degrading activity. The enzyme Aly35 and its truncations Aly35-CD1 and Aly35-CD2 will be useful tools for structural analyses and for preparing bioactive oligosaccharides, especially Aly35-CD1 can be used to prepare G unit–rich oligosaccharides from alginate. [ABSTRACT FROM AUTHOR]

Oligotrophs are predominant in nutrient-poor environments, but copiotrophic bacteria may tolerate conditions of low energy and can also survive and thrive in these nutrient-limited conditions. In the present study, we isolated 648 strains using a dilution plating method after enrichment for low-nutrient conditions. We collected 150 seawater samples at 21 stations in different parts of the water column at the Zhenbei Seamount in the South China Sea. The 648 isolated copiotrophic strains that could grow on low-nutrient medium were in 21 genera and 42 species. A total of 99.4% (644/648) of the bacteria were in the phylum Pseudomonadota, with 73.3% (472/644) in the class Gammaproteobacteria and 26.7% (172/644) in the class Alphaproteobacteria. Among the 42 representative isolates, Pseudoalteromonas arabiensis, Roseibium aggregatum, and Vibrio neocaledonicus were present in all layers of seawater and at almost all of the stations. Almost half of these species (20/42) contained genes that performed nitrate reduction, with confirmation by nitrate reduction testing. These isolates also contained genes that functioned in sulfur metabolism, including sulfate reduction, thiosulfate oxidation, thiosulfate disproportionation, and dimethylsulfoniopropionate degradation. GH23, CBM50, GT4, GT2, and GT51 were the main carbohydrate-active enzymes (CAZymes), and these five enzymes were present in all or almost all of the isolated strains. The most abundant classes of CAZymes were those associated with the degradation of chitin, starch, and cellulose. Collectively, our study of marine copiotrophic bacteria capable of growing on low-nutrient medium demonstrated the diversity of these species and their potential metabolic characteristics. [ABSTRACT FROM AUTHOR]

Alkaline phosphatase (ALP) of the PhoA family is an important enzyme in mammals, microalgae, and certain marine bacteria. It plays a crucial role in the dephosphorylation of lipopolysaccharides (LPS) and nucleotides, which overstimulate cell signaling pathways and cause tissue inflammation in animals and humans. Insufficient ALP activity and expression levels have been linked to various disorders. This study aims to produce recombinant ALP from the marine bacterium Cobetia amphilecti KMM 296 (CmAP) in transformed leaves and calli of Nicotiana tabacum and to elucidate the influence of the plant host on its physical and chemical properties. N. tabacum has proven to be versatile and is extensively used as a heterologous host in molecular farming. The alp gene encoding for CmAP was cloned into the binary vectors pEff and pHREAC and transformed into N. tabacum leaves through agroinfiltration and the leaf disc method for callus induction using Agrobacterium tumefaciens strain EHA105. Transformed plants were screened for recombinant CmAP (rCmAP) production by its enzymatic activity and protein electrophoresis, corresponding to 55 kDa of mature CmAP. A higher rCmAP activity (14.6 U/mg) was detected in a homogenate of leaves bearing the pEFF-CmAP construct, which was further purified 150-fold using metal affinity, followed by anion exchange chromatography. Enzymatic activity and stability were assessed at different temperatures (15–75 °C) and exposure times (≤1 h), with different buffers, pHs, divalent metal ions, and salt concentrations. The results show that rCmAP is relatively thermostable, retaining its activity at 15–45 °C for up to 1 h. Its activity is highest in Tris HCl (pH 9.0–11.0) at 35 °C for 40 min. rCmAP shows higher salt-tolerance and divalent metal-dependence than obtained in Escherichia coli. This can be further explored for cost-effective and massively scalable production of LPS-free CmAP for possible biomedical and agricultural applications. [ABSTRACT FROM AUTHOR]

Highlights: The anammox process has significant potential to treat nitrogen-rich marine RAS WW. The marine anammox species Ca. Scalindua demonstrated effective treatment of synthetic WW with high NO3− levels typically encountered in RAS, at a laboratory scale. Despite a relative decline in the population over time, Ca. Scalindua remained a key species within the anammox granules and sustained a high nitrogen removal rate over a period of 262 days of exposure to elevated NO3− levels. Recirculating aquaculture systems (RAS) hold significant potential for sustainable aquaculture by providing a stable, controlled environment that supports optimal fish growth and welfare. In RAS, ammonium (NH4+) is biologically converted into nitrate (NO3−) via nitrite (NO2−) by nitrifying bacteria. As a result, NO3− usually accumulates in RAS and must subsequently be removed through denitrification in full RAS, or by regular water exchanges in partial RAS. The marine anammox bacteria Candidatus Scalindua can directly convert toxic NH4+ and NO2− into harmless nitrogen gas (N2) and has previously been identified as a promising alternative to the complex denitrification process or unsustainable frequent water exchanges in marine RAS. In this study, we evaluated the impact of high NO3− levels typically encountered in RAS on the performance and abundance of Ca. Scalindua in a laboratory-scale bioreactor. The bacterial composition of the granules, including the relative abundance of key nitrogen-cycling taxa, was analyzed along with the functional profile (i.e., NH4+ and NO2− removal efficiencies). For this purpose, a bioreactor was inoculated and fed a synthetic feed, enriched in NH4+, NO2−, minerals and trace elements until stabilization (Phase 1, 52 days). NO3− concentrations were then gradually increased to 400 mg·L−1 NO3−-N (Phase 2, 52 days), after which the reactor was followed for another 262 days (Phase 3). The reactor maintained high removal efficiencies; 88.0 ± 8.6% for NH4+ and 97.4 ± 1.7% for NO2− in Phase 2, and 95.0 ± 6.5% for NH4+ and 98.6 ± 2.7% for NO2− in Phase 3. The relative abundance of Ca. Scalindua decreased from 22.7% to 10.2% by the end of Phase 3. This was likely due to slower growth of Ca. Scalindua compared to heterotrophic bacteria present in the granule, which could use NO3− as a nitrogen source. Fluorescence in situ hybridization confirmed the presence of a stable population of Ca. Scalindua, which maintained high and stable NH4+ and NO2− removal efficiencies. These findings support the potential of Ca. Scalindua as an alternative filtering technology in marine RAS. Future studies should investigate pilot-scale applications under real-world conditions. [ABSTRACT FROM AUTHOR]

Multifaceted interactions between marine bacteria and particulate matter exert a major control over the biogeochemical cycles in the oceans. At the microbial scale, free-living bacteria benefit from encountering and harnessing the plumes around nutrient-releasing particles, like phyto-plankton and organic aggregates. However, our understanding of the bacterial potential to reshape these eutrophic microhabitats remains poor, in part because of the traditional focus on fast-moving particles that generate ephemeral plumes with lifetime shorter than the uptake timescale. Here we develop a novel hybrid model to assess the impacts of nutrient uptake by clustered free-living bacteria on the nutrient field around slow-moving particles. We integrate a physics-based nutrient transport model with data-derived bacterial distributions at the single-particle level. We inferred the functional form of the bacterial distribution and extracted parameters from published datasets of in vitro and in silico microscale experiments. Based on available data, we find that exponential radial distribution functions properly represent bacterial microzones, but also capture the trend and variation for the exposure of bacteria to nutrients around sinking particles. Our computational analysis provides fundamental insight into the conditions under which free-living bacteria may significantly reshape plumes around marine aggregates in terms of the particle size and sinking velocity, the nutrient diffusivity, and the bacterial trophic lifestyle (oligotrophs < mesotrophs < copiotrophs). A high potential is predicted for chemotactic copiotrophs like Vibrio sp. that achieve fast uptake and strong clustering. This microscale phenomenon can be critical for the microbiome and nutrient cycling in marine ecosystems, especially during particulate blooms. Author summary: Recent lines of evidence highlight the pronounced impact of slow-moving particles on the oceanic carbon cycle and associated ecosystem functions (e.g., CO2 removal, oxygenation, acidification). In contrast to fast ones, slow-moving particles generate large and persistent eutrophic plumes of dissolved organic matter (DOM) and host intense interactions between surface-attached and free-living bacteria. However, significant aspects of the multifaceted biochemical coupling in these eutrophic microhabitats remain largely unexplored. Here we elucidate the potential of free-living bacteria to reshape microscale eutrophic plumes with a particle-level model that combines a physics-based description of the chemical field with a data-based description of bacterial clusters. This hybrid framework captures salient features and impacts of bacterial clustering in a simple and efficient manner, while bypassing inherent uncertainties of more sophisticated bacterial transport models. Our computational analysis delineates the conditions and types of particles, bacteria, and DOM for which plume reshaping is expected to be important. [ABSTRACT FROM AUTHOR]

The development of antibacterial and antiviral high‐entropy alloys (HEAs) incorporating copper has attracted widespread attention. However, the segregation of Cu in HEAs can result in detrimental effects on their mechanical properties and corrosion resistance. Herein, two novel HEAs, CoCrCu0.3FeNi‐Ag(1.8 wt.%) (Cu‐AgHEA) and CoCrFeNi‐Ag0.6 (AgHEA), are designed to address these concerns. The yield strength of Cu‐AgHEA is approximately 400 MPa, surpassing those of CoCrCuFeNi (CuHEA) by 1.3 times, and 304 stainless steel by 1.9 times. The abiotic corrosion resistance of Cu‐AgHEA is one order of magnitude greater than that of CuHEA. Moreover, Cu‐AgHEA demonstrates a remarkable antibacterial efficacy of 99.9% against marine bacteria, surpassing that of AgHEA. The very good bactericidal effect of Cu‐AgHEA is attributed to the increased release of Cu and Ag ions, leading to higher concentrations of reactive oxygen species causing bacterial cell damage. Furthermore, Cu‐AgHEA imparts remarkable antiviral characteristics. After 24‐hour treatment, the Cu‐AgHEA surface effectively deactivated approximately 99% of SARS‐CoV‐2 (COVID‐19) virus, rendering it non‐infectious. These findings present an attractive route to advance materials that integrate structure and function, resulting in exceptional overall performances. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) have been detected in various aquatic environments and negatively affect organisms, including marine luminous bacteria. This study investigated the differences in bioluminescence patterns, cell viability, and biofilm formation of Photobacterium leiognathi strains (LB01 and LB09) when exposed to various concentrations of ground microplastics (GMPs; 0.25%, 0.50%, 1%, or 2% [w/v] per mL) at 22°C or 30°C for 3.1 days (75 h) and 7 days. The strains exhibited heterogenous responses, including variable bioluminescence patterns, cell viability, and biofilm formation, due to the GMPs having effects such as hormesis and bioluminescence quenching. Moreover, the bioluminescence and cell viability differed between the two strains, possibly involving distinct cellular mechanisms, suggesting that GMPs affect factors that influence quorum sensing. Furthermore, the biofilm formation of LB01 and LB09 was observed following exposure to GMPs. Both strains showed increased biofilm formation at higher GMP concentrations (1% and 2%) after 3.1 days at 30°C and 22°C. However, in the 7-day experiment, LB01 significantly (p < 0.05) increased biofilms at 22°C, while LB09 significantly (p < 0.05) produced biofilms at 30°C. These findings highlight the strain-specific responses of Phb. leiognathi to MP pollutants. Therefore, this study underscores the importance of evaluating MPs as environmental stressors on marine microorganisms and their role in the ecophysiological repercussions of plastic pollution in aquatic environments. [ABSTRACT FROM AUTHOR]

The house fly is known to be a vector of antibiotic-resistant bacteria (ARB) in animal farms. It is also possible that the house fly contributes to the spread of ARB and antibiotic resistance genes (ARGs) among various environments. We hypothesized that ARB and ARGs present in marine fish and fishery food may gain access to humans via the house fly. We show herein that pAQU1, a marine bacterial ARG-bearing plasmid, persists in the house fly intestine for 5 days after fly ingestion of marine bacteria. In the case of Escherichia coli bearing the same plasmid, the persistence period exceeded 7 days. This interval is sufficient for transmission to human environments, meaning that the house fly is capable of serving as a vector of marine-derived ARGs. Time course monitoring of the house fly intestinal microflora showed that the initial microflora was occupied abundantly with Enterobacteriaceae. Experimentally ingested bacteria dominated the intestinal environment immediately following ingestion; however, after 72 h, the intestinal microflora recovered to resemble that observed at baseline, when diverse genera of Enterobacteriaceae were seen. Given that pAQU1 in marine bacteria and E. coli were detected in fly excrement (defined here as any combination of feces and regurgitated material) at 7 days post-bacterial ingestion, we hypothesize that the house fly may serve as a vector for transmission of ARGs from marine items and fish to humans via contamination with fly excrement. [ABSTRACT FROM AUTHOR]

Marine bacteria release exopolymeric substances (EPS) molecules released in response to the harsh environmental conditions of the environment as a survival strategy. Nitrogen or carbon sources affects the metabolic synthesis of EPS in microorganisms. In this study, 2 different nutritional sources were used to extract EPS from a marine bacterium associated with the sponge Hyrtios erectus collected from the Red Sea. The antibacterial activity and chemical composition of the EPS from Bacillus subtilis M5 grown in Zobell marine broth (ZBE) and nutrient broth (NBE) was studied. The organism demonstrated potential activity against tested pathogenic bacteria. We observed differences in the antibacterial activity and the chemical composition of EPS polymers isolated from the organism. Fourier transform infrared (FTIR) spectrum revealed the peaks for carbonyl, alkyl and hydroxyl functional groups confirming the presence of functional groups characteristic of polysaccharides. Minor differences was observed in the relative intensities and slight peak shifts between the two spectra may be attributed to variations in the specific EPS compositions or extraction conditions. Scanning electron microscopic images revealed crystalline and amorphous characteristics of EPS for ZBE and NBE respectively. Only little differences were observed between the two EPS biopolymers both in antibacterial activity and chemical composition. [ABSTRACT FROM AUTHOR]

Vibrio sp. KMM 8419 (=CB1-14) is a Gram-negative bacterium isolated from a food-net mucus sample of marine polychaete Chaetopterus cautus collected in the Sea of Japan. Here, we report the structure and biosynthetic gene cluster of the capsular polysaccharide (CPS) from strain KMM 8419. The CPS was isolated and studied by one- and two-dimensional 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The molecular weight of the CPS was about 254 kDa. The CPS consisted of disaccharide repeating units of D-glucose and sulfated and acetylated L-rhamnose established as →2)-α-L-Rhap3S4Ac-(1→6)-α-D-Glcp-(1→. To identify the genes responsible for CPS biosynthesis, whole-genome sequencing of KMM 8419 was carried out. Based on the genome annotations together with the Interproscan, UniProt and AntiSMASH results, a CPS-related gene cluster of 80 genes was found on chromosome 1. This cluster contained sets of genes encoding for the nucleotide sugar biosynthesis (UDP-Glc and dTDP-Rha), assembly (glycosyltransferases (GT)), transport (ABC transporter) and sulfation (PAPS biosynthesis and sulfotransferases) of the sulfated CPS. A hypothetical model for the assembly and transportation of the sulfated CPS was also proposed. In addition, this locus included genes for O-antigen biosynthesis. Further studies of biological activity, the structure–activity relationship in the new sulfated polysaccharide and its biosynthesis are necessary for the development of potent anticancer agents or drug delivery systems. [ABSTRACT FROM AUTHOR]

The strain DAU334T, which was obtained from samples of sea water and sediments collected from the East Sea in the Republic of Korea, is a rod-shaped, Gram-stain-negative bacterium. It is facultative and positive for the oxidase and catalase enzymes. Based on the analysis of 16S rRNA sequences, it was determined that strain DAU334T had the highest degree of similarity to several strains of Shewanella species, i.e., S. schlegeliana HRKA1T (99%), S. halifaxensis HAE-EB4T (99%), S. pneumatophori SCRC-2738T (99%), S. sairae SM2-1T (99%), and S. marinintestina IK-1T (1419/1440, 99%), respectively. The complete genome sequence consisted of one contig with 4 343 646 bp, and the genome G+C content was 43.12%. The average nucleotide identity (ANI), digital DNA-DNA hybridization (dDDH), and average amino acid identity (AAI) between strain DAU334T and its closest relatives were 77.85‒71.10, 82.14‒67.07, and 22.60‒19.70%, respectively. The major fatty acids (>10%) of strain DAU334T were iso-C13:0 and Summed feature 3 (C16:1 w7c and/or C16:1 w6c). The respiratory quinones were ubiquinone 7 (Q7), ubiquinone 8 (Q8), menaquinone 7 (MK-7), menaquinone 8 (MK-8), methylated menaquinone 7 (MMK-7), and an unidentified one. According to the results of polyphasic analyses, the strain DAU334T belongs to a novel species within the genus Shewanella, for which the name Shewanellayoungdeokensis sp. nov. (type strain DAU334T = KCTC 72428T = JCM 35745T = KCCM 43479T) is proposed. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides (AMPs) have become a viable source of novel antibiotics that are effective against human pathogenic bacteria. In this study, we construct a bank of culturable marine biofilm bacteria constituting 713 strains and their nearly complete genomes and predict AMPs using ribosome profiling and deep learning. Compared with previous approaches, ribosome profiling has improved the identification and validation of small open reading frames (sORFs) for AMP prediction. Among the 80,430 expressed sORFs, 341 are identified as candidate AMPs with high probability. Most potential AMPs have less than 40% similarity in their amino acid sequence compared to those listed in public databases. Furthermore, these AMPs are associated with bacterial groups that are not previously known to produce AMPs. Therefore, our deep learning model has acquired characteristics of unfamiliar AMPs. Chemical synthesis of 60 potential AMP sequences yields 54 compounds with antimicrobial activity, including potent inhibitory effects on various drug‐resistant human pathogens. This study extends the range of AMP compounds by investigating marine biofilm microbiomes using a novel approach, accelerating AMP discovery. Highlights: Bacterial isolation, cultivation, and genome sequencing have laid the foundation for antimicrobial peptide (AMP) discovery from marine biofilms, where AMPs are largely unexplored.The incorporation of ribosome profiling has enhanced the sequence filtering process, enabling more accurate identification of small open reading frames before AMP prediction.A multilayered model‐based filtering pipeline exhibits outstanding predictive performance in screening candidate AMPs.Experimentally validated AMPs show excellent antibacterial efficacy, highlighting their potential as candidate drugs. [ABSTRACT FROM AUTHOR]

This study examined the influence of Bacillus subtilis adhesion on the corrosion and cavitation erosion resistance of high-velocity oxy-fuel (HVOF) sprayed WC-10Co-4Cr coatings. The polished HVOF-sprayed WC-10Co-4Cr coatings were divided into two groups: one immersed in artificial seawater (ASW) and the other immersed in ASW containing Bacillus subtilis (BASW). Following an immersion period of 42 days, chromium oxide was detected on the ASW-immersed coating according to x-ray diffraction, while the BASW-immersed coating showed no signs of oxidation or corrosion. Electrochemical testing indicated compromised corrosion resistance in both the coatings. Nonetheless, the corrosion resistance of the BASW-immersed coating was much better than the ASW-immersed coating, suggesting that the Bacillus subtilis biofilm protected the coating surface from the corrosive substances in ASW, such as chloride ions and oxygen. Cavitation erosion testing revealed that prior immersion in ASW accelerated the erosion process, while the BASW-immersed coating displayed better resistance to cavitation erosion due to the inhibited corrosion attained by the Bacillus subtilis biofilm. [ABSTRACT FROM AUTHOR]

In this study, we introduce Bacillus enclensis AGM_Cr8, a gram-positive marine bacterium isolated from the chronically polluted Versova Creek in Mumbai, India. AGM_Cr8 exhibits robust tolerance to chromate stress, thriving in marine agar media containing up to 3200 mg/l of hexavalent chromium [Cr(VI)], with the Minimum Inhibitory Concentration (MIC) established at 5000 mg/l. Notably, AGM_Cr8 also displays tolerance to other heavy metals, including Lead [Pb (II)] (1200 mg/l), Arsenic [As (III)] (400 mg/l), Cadmium [Cd(II)] (100 mg/l), and Nickel [Ni(II)] (100 mg/l). Scanning Electron Microscopy (SEM) reveals the presence of Cr(VI) on the bacterial surface, accompanied by the secretion of extracellular polymeric substances (EPSs) facilitating Cr(VI) sequestration. This observation is validated through Energy Dispersive Spectroscopy (EDS). Transmission Electron Microscopy (TEM) and Scanning Transmission Electron Microscopy–Energy Dispersive Spectroscopy (STEM-EDS) confirm internal bioaccumulation of Cr(VI). X-ray photoelectron spectroscopy (XPS) identifies distinct peaks around 579 and 576 eV, indicating the coexistence of Cr(VI) and Cr(III), implying a bioreduction mechanism. De novo genome sequencing identifies twenty-two chromate-responsive genes, including putative chromate transporters (srpC1 and srpC2), suggesting an efflux mechanism. Other identified genes encode NAD(P)H-dependent FMN-containing oxidoreductase, NADH quinone reductase, ornithine aminotransferase, transporter genes (natA, natB, ytrB), and genes related to DNA replication and repair (recF), DNA mismatch repair (mutH), and superoxide dismutase. We therefore, propose a chromate detoxification pathway that involves an interplay of chromate transporters, enzymatic reduction of Cr(VI) to Cr(III), DNA repair and role of antioxidants in response to chromate stress. We have highlighted the potential of AGM_Cr8 for bioremediation in chromium-contaminated environments, given its robust tolerance and elucidated molecular mechanisms for detoxification. [ABSTRACT FROM AUTHOR]

Brazil is one of the largest oil producers in the world, and petroleum exploration is predominant in marine environments, mainly in the city of Rio de Janeiro. These environments become vulnerable to oil spills, which can be remedied by petroleum hydrocarbon-degrading bacteria. To better understand the distribution of polycyclic aromatic hydrocarbon (PAH)-degrading bacteria in these marine environments, water samples were collected from eight beaches (Arpoador, Grumari, Vermelha, Sahy, Itacuruçá, Itaipuaçu, Ferradura, and Itaipu) along the Rio de Janeiro coastline and further contaminated with 0.1% naphthalene, used as a PAH model. Naphthalene-enriched bacteria were isolated in marine agar, identified using 16S rRNA sequencing, and tested for emulsification and naphthalene degradation. Thirty-five different genera were observed among the 231 isolates, most belonging to Proteobacteria. Some genera were found in at least half of the studied beaches, such as Mesoflavibacter, Muricauda, Alteromonas, Salipiger, Pseudooceanicola, and Celeribacter, while others were found in only a few water samples. Seventeen and 18 strains were considered to be positive for naphthalene degradation and emulsification, respectively, making them the most promising strains for naphthalene bioremediation. Five of these strains were positive for both degradation and emulsification. This study contributes to the selection of potential candidates for further studies on the remediation of PAHs in tropical marine environments worldwide. [ABSTRACT FROM AUTHOR]

Simple Summary: This study addresses the growing problems of pesticide usage, such as environmental pollution and pest resistance. The Fall Armyworm (Spodoptera frugiperda) is an insect known for damaging maize crops and withstanding chemical treatments. Traditional pesticides have become less effective, leading researchers to explore natural, bacteria-based solutions. The study aimed to test if certain types of bacteria found in marine environments could live within maize plants and protect them from this pest. In our study, these bacteria were applied to the plants in four different ways: spraying on leaves, treating seeds, drenching soil, and a combination of all three. The results showed that the bacteria, particularly Bacillus sp. Esh39 and Bacillus tequilensis R39, caused significant mortality in laboratory tests. However, while effective in reducing pests, the bacteria did not notably boost plant growth. The study highlights that using these natural bacteria could be a sustainable alternative to chemical pesticides, offering new ways to protect crops and lessen environmental impact. Further research could strengthen this natural method of insect control, potentially benefiting agriculture and reducing dependency on synthetic pesticides. The widespread use of pesticides to manage Spodoptera frugiperda has led to significant challenges. This insect has developed resistance to 47 active insecticide ingredients. Therefore, endophytic entomopathogenic bacteria have been explored as an alternative pest management strategy, offering the potential to reduce reliance on chemical pesticides. The current study aims to evaluate the colonization potential of indigenous marine Bacillus strains as endophytes in maize plants and to assess their insecticidal activity against S. frugiperda. Four inoculation methods—foliar application, seed treatment, soil drenching, and a combination of all three—were used to establish the Bacillus strains as endophytes in maize plants. Our results showed that the promising native Bacillus strains exhibited both antibacterial and insecticidal effects against S. frugiperda neonates under laboratory conditions. Foliar application of Bacillus sp. Esh39 caused the highest mortality rate (65%), followed by Bacillus tequilensis R39 (60%). However, this method did not significantly enhance plant height or chlorophyll content. The potential of these native Bacillus strains warrants further investigation to improve biological control via endophytic mediation. Our findings provide valuable insights into the bacterial diversity and functionality of mangrove ecosystems and pave the way for innovative, sustainable insect management strategies. [ABSTRACT FROM AUTHOR]

Genome streamlining, i.e. genome size reduction, is observed in bacteria with very different life traits, including endosymbiotic bacteria and several marine bacteria, raising the question of its evolutionary origin. None of the hypotheses proposed in the literature is firmly established, mainly due to the many confounding factors related to the diverse habitats of species with streamlined genomes. Computational models may help overcome these difficulties and rigorously test hypotheses. In this work, we used Aevol, a platform designed to study the evolution of genome architecture, to test 2 main hypotheses: that an increase in population size (N) or mutation rate (μ) could cause genome reduction. In our experiments, both conditions lead to streamlining but have very different resulting genome structures. Under increased population sizes, genomes lose a significant fraction of noncoding sequences but maintain their coding size, resulting in densely packed genomes (akin to streamlined marine bacteria genomes). By contrast, under an increased mutation rate, genomes lose both coding and noncoding sequences (akin to endosymbiotic bacteria genomes). Hence, both factors lead to an overall reduction in genome size, but the coding density of the genome appears to be determined by N × μ ⁠. Thus, a broad range of genome size and density can be achieved by different combinations of N and μ. Our results suggest that genome size and coding density are determined by the interplay between selection for phenotypic adaptation and selection for robustness. [ABSTRACT FROM AUTHOR]

The spillage of petroleum hydrocarbons, one of the most versatile energy resources, leads to disastrous environmental pollution. The present study aims to degrade oil using enzymes from bacterial strains. A total of 39 bacteria were isolated from six different soil samples collected from Ullal Beach, Mangalore, Karnataka, located at 12°52′N latitude and 74°49′E longitude, India. All 39 bacterial isolates were screened for the production of four industrially important extracellular enzymes. Among these isolates, ten showed the highest lipase production. These cultures were further screened for bio-surfactant assays, including oil displacement and drop collapse assay and Emulsification Index. EBPL0613-F2 exhibited the best reaction in crude oil degradation. A polyphasic taxonomical approach identified the crude oil-degrading bacterium EBPL0613-F2 as Bacillus licheniformis and submitted in NCBI and the Accession Number is PP059616. It was then cultivated in ocean water media with tween 20 and 1% crude oil as the sole carbon and energy source. The strain was screened for lipase quantitative and qualitative assay and the protein content was also estimated. The identified bacterial strain Bacillus licheniformis EBPL0613-F2 demonstrated moderate lipase activity, with 76 U/ml and 24 U/ml, respectively, after 48–72 h of incubation in the crude oil substrate. For Tween 20 substrates, it exhibited 36 U/ml and 34 U/ml, respectively. FTIR analysis was used to examine the properties of crude oil following the biodegradation. The results suggest that, EBPL0613-F2 recorded the highest degradation rate so this culture has the potential for use in the degradation of crude oil in a greener manner. [ABSTRACT FROM AUTHOR]

Microbial diversity plays key role in marine ecosystems, and quantifying the impact of plastic pollution on these organisms is essential to better anticipate and manage threats to these fragile ecosystems. In nine simplified tropical ecosystems (i.e. mesocosms), we tested a concentration gradient of macroplastics reflecting the amount of plastic released by pearl farms. In each mesocosm, we collected bacterial samples from three different compartments: macroplastics, water and animals, Tridacna maxima. The objective was to test how plastic concentration influences the bacterial community, whether certain bacteria respond similarly across these compartments, and to define a threshold concentration of plastic that would impact marine bacteria. We observed that over 70 % of the variability in the bacterial community was explained by the type of sample (51.8 %) and time (19.4 %). On a finer scale, we found that the abundance of 33 bacterial genera was significantly correlated with plastic pollution, with the highest concentration (4.05 g/L) accounting for the vast majority of the signal. The occurrence of these bacterial genera increased with high plastic concentrations, suggesting imbalanced competitive relationships favoring less pollutant-sensitive genera. Some of these bacteria were shared across compartments and have known ecological functions, including plastic degradation and pathogenicity. Our results align with prior studies that warn plastics can alter microbial interactions and promote the emergence of pathogenic families. [ABSTRACT FROM AUTHOR]

Bacteria assume a pivotal role in mitigating environmental issues associated with heavy metals, microplastics, and pesticides. Within the domain of heavy metals, bacteria exhibit a wide range of processes for bioremediation, encompassing biosorption, bioaccumulation, and biotransformation. Toxigenic metal ions can be effectively sequestered, transformed, and immobilized, hence reducing their adverse environmental effects. Furthermore, bacteria are increasingly recognized as significant contributors to the process of biodegradation of microplastics, which are becoming increasingly prevalent as contaminants in marine environments. These microbial communities play a crucial role in the colonization, depolymerization, and assimilation processes of microplastic polymers, hence contributing to their eventual mineralization. In the realm of pesticides, bacteria play a significant role in the advancement of environmentally sustainable biopesticides and the biodegradation of synthetic pesticides, thereby mitigating their environmentally persistent nature and associated detrimental effects. Gaining a comprehensive understanding of the intricate dynamics between bacteria and anthropogenic contaminants is of paramount importance in the pursuit of technologically advanced and environmentally sustainable management approaches. [ABSTRACT FROM AUTHOR]

This study is aimed at the development of a fermented cashew nut cheese alternative supplemented with Chondrus crispus and Porphyra sp. and the evaluation of the impact of seaweed supplementation through analysis of physicochemical, microbiological, and organoleptic properties of the developed food products. The total lipid content decreased with the supplementation with seaweeds. Crude protein content also slightly decreased, while elemental analysis showed that mineral and trace element (Ca, K, Mg, Na, Fe, I, Se, and Zn) content increased when C. crispus was added to the paste. The analyses of color and textural (TPA) attributes showed that these were significantly influenced by adding seaweeds to the cashew paste. Generally, the microbiological results comply with the different European guidelines for assessing the microbiological safety of ready-to-eat foods placed on the market, except for aerobic mesophilic bacteria and marine agar counts. Flash Profile analysis allowed for distinguishing sample attributes, showing an increased flavor complexity of the plant-based cheese alternatives supplemented with seaweeds. Overall, the study indicates that seaweed enrichment mainly influenced the physicochemical and sensory characteristics of plant-based cheese alternatives. [ABSTRACT FROM AUTHOR]

A Gram-stain-negative, non-motile, aerobic, pale-yellow coloured and oval-shaped bacterium designated GRR-S6-38T was isolated from a tidal flat sediment that collected from Garorim Bay of the Yellow Sea, Republic of Korea. Strain GRR-S6-38T grew at 15–40 °C (optimum, 30 °C) at pH 6–9 (optimum, pH 7) and at 2–6% (w/v) NaCl (optimum, 2% NaCl). Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain GRR-S6-38T was closely related to those of J. seosinensis CL-SP26T (98.1%), J. helgolandensis DSM 14858T (97.4%), J. rubra CECT 5088T (97.4%), J. faecimaris DSM 100420T (97.4%), J. marina SHC163T (97.3%), J. donghaensis CECT 7802T (97.2%) and J. pohangensis DSM 19073T (97.1%). The average nucleotide identity and digital DNA-DNA hybridization value between GRR-S6-38T and related type strains were 71.47–78.59% and 17.80–21.40%. Strain GRR-S6-38T was characterized as having Q-10 as the predominant respiratory quinone and the major principle fatty acids (> 10%) were SF 8 (C18:1ω7c/C18:1ω6c, 39.3%), C19:0ω8c cyclo (13.2%) and C18:1ω7c 11-methyl (10.6%). The polar lipids consisted of diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, an unidentified lipid, two unidentified aminolipids and two unidentified phospholipids. The assembled genome of strain GRR-S6-38T has a total length of 3.32 Mbp, and a G + C content is 69.98%. Based on the polyphasic taxonomic evidence presented in this study, GRR-S6-38T is regarded to represent a novel species within the genus Jannaschia, for which name Jannaschia ovalis sp. nov. is proposed. The type strain is GRR-S6-38T (= KCTC 82518 = KACC 22240 = JCM 36187). [ABSTRACT FROM AUTHOR]

Background: In microbial cell factories, substrate accessibility to enzyme is a key factor affecting the biosynthesis of natural products. As a robust chassis cells for biofuels and bioproducts, Saccharomyces cerevisiae also encounters the challenge since different enzymes and precursors are typically compartmentalized in different organelles. Such spatial separation could largely limit the efficiency of enzymatic reactions. In this study, the production of the hydrophobic product (vitamin A) was highly improved by metabolic engineering combined with degrading lipid droplets (the primary organelle storing β-carotene) to achieve efficient contact between β-carotene and 15, 15'-β-carotene monooxygenases in Saccharomyces cerevisiae. Results: To efficiently produce vitamin A in Saccharomyces cerevisiae, ten 15, 15'-β-carotene monooxygenases (BCMOs) were firstly evaluated. The strain carrying marine bacterium 66A03 (Mb. BCMO) achieved the highest vitamin A titer. Co-adding 10% dodecane and 1% dibutylhydroxytoluene increased vitamin A titer to 19.03 mg/L in two-phase fermentation. Since most β-carotene is stored in LDs while BCMO is located in the cytosol, we developed a strategy to release β-carotene from LDs to better contact with BCMO. By overexpressing TGL3 and TGL4 using an ion-responsive promoter after high accumulation of β-carotene in LDs, LDs were sequentially degraded, which dramatically improved vitamin A production. Finally, by overexpressing tHMG1, ERG20, and CrtI and introducing Vitreoscilla hemoglobin, vitamin A titer reached 219.27 mg/L, which was a 10.52-folds increase over the original strain in shake flasks, and finally reached 1100.83 mg/L in fed-batch fermentation. The effectiveness of LDs degradation on promoting the formation of β-carotene cleaved product has also been verified in β-ionone synthesis with 44.07% increased yield. Conclusions: Overall, our results highlighted the significance of sequential degrading LDs on vitamin A overproduction in recombinant yeast, and verified that combining metabolic and LDs engineering is an efficient strategy to improve vitamin A production. This integrated strategy can be applied to the overproduction of other hydrophobic compounds with similar characteristics. [ABSTRACT FROM AUTHOR]