Marine Microbial Research Articles

Impact of Bioactive Compounds in the Management of Various Inflammatory Diseases.

Inflammation is an individual's physiological response to a sequence of physical, chemical, or infectious stressors acting mainly to provide localized protection. Although inflammation is a protective and thus beneficial process, its excess or prolonged action can be harmful to the body. An increasing number of the population worldwide are changing their lifestyles, which leads to a rise in inflammatory diseases, such as atherosclerosis, angina pectoris, myocardial infarction, ulcerative colitis, cancer, and many more. Their treatment is based majorly on the pharmacological approach. However, natural products or bioactive compounds are of great significance in inflammation therapy because they show minimum side effects and maximum bioavailability. Therefore, it is critical to investigate bioactive substances that can modify target functions associated with oxidative stress defense and might be used to achieve various health benefits. This review accentuates the essence of bioactive chemicals used in the treatment of inflammation and other inflammatory illnesses. These bioactive compounds can be of any origin, such as plants, animals, bacteria, fungi, marine invertebrates, etc. Bioactive compounds derived from plant sources, such as glycyrrhizin, lignans, lycopene, resveratrol, indoles, and phenolic and polyphenolic compounds, work mainly by reducing oxidative stress and thereby preventing various inflammatory disorders. A large diversity of these anti-inflammatory bioactive compounds has also been discovered in marine environments, giving rise to an increase in the interest of various scientists in marine invertebrates and microbes. The vast diversity of microbes found in the marine environment represents an enormous supply to extract novel compounds, such as from bacteria, cyanobacteria, fungi, algae, microalgae, tiny invertebrates, etc. In the present review, an attempt has been made to summarize such novel bioactive compounds that help prevent inflammatory responses via different mechanisms of action.

How Viruses Shape Microbial Plankton Microdiversity.

One major conundrum of modern microbiology is the large pangenome (gene pool) present in microbes, which is much larger than those found in complex organisms such as humans. Here, we argue that this diversity of gene pools carried by different strains is maintained largely due to the control exercised by viral predation. Viruses maintain a high strain diversity through time that we describe as constant-diversity equilibrium, preventing the hoarding of resources by specific clones. Thus, viruses facilitate the release and degradation of dissolved organic matter in the ocean, which may lead to better ecosystem functioning by linking top-down to bottom-up control. By maintaining this equilibrium, viruses act as a key element of the adaptation of marine microbes to their environment and likely evolve as a single evolutionary unit.

Microdiversity in marine pelagic ammonia-oxidizing archaeal populations in a Mediterranean long-read metagenome.

The knowledge of the different population-level processes operating within a species, and the genetic variability of the individual prokaryotic genomes, is key to understanding the adaptability of microbial populations. Here, we characterized the flexible genome of ammonia-oxidizing archaeal (AOA) populations using a metagenomic recruitment approach and long-read (PacBio HiFi) metagenomic sequencing. In the lower photic zone of the western Mediterranean Sea (75 m deep), the genomes Nitrosopelagicus brevis CN25 and Nitrosopumilus catalinensis SPOT1 had the highest recruitment values among available complete AOA genomes. They were used to analyse the diversity of flexible genes (variable from strain to strain) by examining the long-reads located within the flexible genomic islands (fGIs) identified by their under-recruitment. Both AOA genomes had a large fGI involved in the glycosylation of exposed structures, highly variable, and rich in glycosyltransferases. N. brevis had two fGIs related to the transport of phosphorus and ammonium respectively. N. catalinensis had fGIs involved in phosphorus transportation and metal uptake. A fGI5 previously reported as 'unassigned function' in N. brevis could be associated with defense. These findings demonstrate that the microdiversity of marine microbe populations, including AOA, can be effectively characterized using an approach that incorporates third-generation sequencing metagenomics.

INFLUENCE OF ULTRAFINE PARTICLES OF SILICON IV OXIDE (SiO2) AND OAK BARK EXTRACT ON BACTERIAL LUMINESCENCE

Background. Phytobiotic additives and ultrafine particles (UFP), especially of metallic nature, are increasingly used in agriculture as fertilizers and components of feed additives. However, there is very little data about the effect of non-metallic UFP. In particular, silicon-containing UFP have shown high efficiency as plant growth stimulators under stress conditions, but whether they can act as antibacterial agents or as protective agents in microbial ecosystems is unknown. Therefore, the aim of the presented work is to evaluate positive and negative reactions of the model luminescent microorganism Escherichia coli K12 TG1 when exposed to suspensions of silicon IV oxide (SiO2) in various concentrations both in pure form and in combination with phytobiotic additive – oak bark extract. Materials and methods. The luminescence intensity of the recombinant strain of Echerichia coli of the natural marine microorganism Photobacterium leiongnathi with cloned luxCDABE-genes under the influence of concentrations (0.5-0.00024 M) of UFP SiO2 and aqueous extract of oak bark (2-1024 multiples) was studied. Results. It was found that UFP in pure form stimulate bacterial luminescence by 252.2 % with respect to the control in the stationary phase of growth at 0.5 mol/L. They also act as protectors of intracellular metabolism, reducing the inhibitory effect of oak bark extract. The latter in pure form suppresses more than 50 % of bacterial luminescence up to 4-fold dilution (12.5 mg/mL), which determines the possibility of its use as an alternative to antibiotic drugs. Conclusion. UFP SiO2 have pronounced protective properties with respect to microbial community.

Whole-Cell Biosensor for Iron Monitoring as a Potential Tool for Safeguarding Biodiversity in Polar Marine Environments.

Iron is a key micronutrient essential for various essential biological processes. As a consequence, alteration in iron concentration in seawater can deeply influence marine biodiversity. In polar marine environments, where environmental conditions are characterized by low temperatures, the role of iron becomes particularly significant. While iron limitation can negatively influence primary production and nutrient cycling, excessive iron concentrations can lead to harmful algal blooms and oxygen depletion. Furthermore, the growth of certain phytoplankton species can be increased in high-iron-content environments, resulting in altered balance in the marine food web and reduced biodiversity. Although many chemical/physical methods are established for inorganic iron quantification, the determination of the bio-available iron in seawater samples is more suitably carried out using marine microorganisms as biosensors. Despite existing challenges, whole-cell biosensors offer other advantages, such as real-time detection, cost-effectiveness, and ease of manipulation, making them promising tools for monitoring environmental iron levels in polar marine ecosystems. In this review, we discuss fundamental biosensor designs and assemblies, arranging host features, transcription factors, reporter proteins, and detection methods. The progress in the genetic manipulation of iron-responsive regulatory and reporter modules is also addressed to the optimization of the biosensor performance, focusing on the improvement of sensitivity and specificity.

A rationally designed polymer brush/lubricant coating system for effective static and dynamic marine antifouling

Bioinspired slippery surfaces have garnered significant attention as promising solutions to mitigate biofouling. Unlike traditional lubricant-infused porous surfaces, recent research has focused on the integration of lubricants within polymer brush-grafted surfaces. The combination of polydimethylsiloxane (PDMS) polymer brush and silicone oil has gradually become the most prevalent choice due to their outstanding chemical affinity. However, this conventional coating system also has the potential for improvement to meet the needs of long-lasting and efficient marine antifouling, including i) precisely designing the polymer brush’s chemical structure to match the polarity of a specific lubricant enhances their chemical affinity, and ii) appropriately reduce the coating system’s surface energy to improve the fouling desorption performance. Here, we introduce a systematically engineered polymer brush/lubricant coating system that incorporates fluorinated polysiloxane and perfluoropolyether fluid. This novel coating system exhibits enhanced adhesion strength coupled with reduced surface energy, resulting in superior stability and omniphobic properties. Additionally, it showcases excellent corrosion resistance and significantly deters marine microorganism adhesion, achieving reductions of 98.8 % for P. tricornutum and 99.8 % for Bacillus sp.. Marine field trials, conducted over a 90-day static immersion period, confirm the remarkable antifouling performance, which surpasses most existing slippery coatings. Moreover, under dynamic conditions, organisms adhering for 150 days are readily dislodged by shear force. These findings underscore the pivotal role of systematic design in polymer brush/lubricant coating systems for the advancement of high-performance slippery surfaces tailored for marine antifouling applications.

Streptomyces-Fungus Co-Culture Enhances the Production of Borrelidin and Analogs: A Genomic and Metabolomic Approach.

The marine Streptomyces harbor numerous biosynthetic gene clusters (BGCs) with exploitable potential. However, many secondary metabolites cannot be produced under laboratory conditions. Co-culture strategies of marine microorganisms have yielded novel natural products with diverse biological activities. In this study, we explored the metabolic profiles of co-cultures involving Streptomyces sp. 2-85 and Cladosporium sp. 3-22-derived from marine sponges. Combining Global Natural Products Social (GNPS) Molecular Networking analysis with natural product database mining, 35 potential antimicrobial metabolites annotated were detected, 19 of which were exclusive to the co-culture, with a significant increase in production. Notably, the Streptomyces-Fungus interaction led to the increased production of borrelidin and the discovery of several analogs via molecular networking. In this study, borrelidin was first applied to combat Saprolegnia parasitica, which caused saprolegniosis in aquaculture. We noted its superior inhibitory effects on mycelial growth with an EC50 of 0.004 mg/mL and on spore germination with an EC50 of 0.005 mg/mL compared to the commercial fungicide, preliminarily identifying threonyl-tRNA synthetase as its target. Further analysis of the associated gene clusters revealed an incomplete synthesis pathway with missing malonyl-CoA units for condensation within this strain, hinting at the presence of potential compensatory pathways. In conclusion, our findings shed light on the metabolic changes of marine Streptomyces and fungi in co-culture, propose the potential of borrelidin in the control of aquatic diseases, and present new prospects for antifungal applications.

The Phylogeny and Metabolic Potentials of an Aromatics-Degrading Marivivens Bacterium Isolated from Intertidal Seawater in East China Sea.

Lignocellulosic materials, made up of cellulose, hemicellulose, and lignin, constitute some of the most prevalent types of biopolymers in marine ecosystems. The degree to which marine microorganisms participate in the breakdown of lignin and their impact on the cycling of carbon in the oceans is not well understood. Strain LCG002, a novel Marivivens species isolated from Lu Chao Harbor's intertidal seawater, is distinguished by its ability to metabolize lignin and various aromatic compounds, including benzoate, 3-hydroxybenzoate, 4-hydroxybenzoate and phenylacetate. It also demonstrates a broad range of carbon source utilization, including carbohydrates, amino acids and carboxylates. Furthermore, it can oxidize inorganic gases, such as hydrogen and carbon monoxide, providing alternative energy sources in diverse marine environments. Its diversity of nitrogen metabolism is supported by nitrate/nitrite, urea, ammonium, putrescine transporters, as well as assimilatory nitrate reductase. For sulfur assimilation, it employs various pathways to utilize organic and inorganic substrates, including the SOX system and DSMP utilization. Overall, LCG002's metabolic versatility and genetic profile contribute to its ecological significance in marine environments, particularly in the degradation of lignocellulosic material and aromatic monomers.

Study on the screening of marine beneficial bacteria and the inhibition of sulfate-reducing bacteria corrosion in marine oil field produced water

PurposeThe purpose of this study is to provide ideas and theoretical guidance for green, environmentally friendly and efficient “bacteriostasis with bacteria” technology.Design/methodology/approachIn this paper, a beneficial strain of bacteria was extracted and purified from marine mud. Weight-loss test, morphological observation and electrochemical test were used to systematically study the effect of sulfate-reducing bacteria (SRB)-induced corrosion inhibition on X65 steel in simulated offshore oil field production water.FindingsThe results showed that a beneficial strain was selected and identified as Vibrio alginolyticus. Under the condition of co-culture of SRB, the average corrosion rate of X65 steel was significantly reduced. In the mixed bacterial system, the surface of X65 steel samples was relatively flat, and the structure of biofilm and corrosion product film was dense. The number of corrosion pits, the average diameter and depth of corrosion pits were significantly reduced. The localized corrosion of X65 steel was significantly inhibited.Originality/valueThe complex and changing marine environment makes the corrosion problem of marine steel increasingly severe, and the microbiologically influenced corrosion (MIC) caused by SRB is particularly serious. The research and development of environmentally friendly corrosion protection technology is a long-term and difficult problem. The use of beneficial microorganisms to control MIC is a green and efficient anticorrosion measure. Compared with terrestrial microorganisms, marine microorganisms can adapt to complex environments, and their metabolites exhibit special biological activities. The use of marine beneficial bacteria can inhibit SRB activity to achieve the corrosion inhibition effect.

Combined influence of the nanoplastics and polycyclic aromatic hydrocarbons exposure on microbial community in seawater environment

Nanoplastics (NPs) and polycyclic aromatic hydrocarbons (PAHs) are recognized as persistent organic pollutant (POPs) with demonstrated physiological toxicity. When present in aquatic environments, the two pollutants could combine with each other, resulting in cumulative toxicity to organisms. However, the combined impact of NPs and PAHs on microorganisms in seawater is not well understood. In this study, we conducted an exposure experiment to investigate the individual and synergistic effects of NPs and PAHs on the composition, biodiversity, co-occurrence networks of microbial communities in seawater. Exposure of individuals to PAHs led to a reduction in microbial community richness, but an increase in the relative abundance of species linked to PAHs degradation. These PAHs-degradation bacteria acting as keystone species, maintained a microbial network complexity similar to that of the control treatment. Exposure to individual NPs resulted in a reduction in the complexity of microbial networks. Furthermore, when PAHs and NPs were simultaneously present, the toxic effect of NPs hindered the presence of keystone species involved in PAHs degradation, subsequently limiting the degradation of PAHs by marine microorganisms, resulting in a decrease in community diversity and symbiotic network complexity. This situation potentially poses a heightened threat to the ecological stability of marine ecosystems. Our work strengthened the understanding of the combined impact of NPs and PAHs on microorganisms in seawater.

Application of single-cell Raman-deuterium isotope probing to reveal the resistance of marine ammonia-oxidizing archaea SCM1 against common antibiotics

Antimicrobial resistance (AMR) in oceans poses a significant threat to human health through the seafood supply chain. Ammonia-oxidizing archaea (AOA) are important marine microorganisms and play a key role in the biogeochemical nitrogen cycle around the world. However, the AMR of marine AOA to aquicultural antibiotics is poorly explored. Here, Raman-deuterium isotope probing (Raman-DIP), a single-cell tool, was developed to reveal the AMR of a typical marine species of AOA, Nitrosopumilus maritimus (designated SCM1), against six antibiotics, including erythromycin, tetracycline, novobiocin, neomycin, bacitracin, and vancomycin. The D2O concentration (30% v/v) and culture period (9 days) were optimized for the precise detection of metabolic activity in SCM1 cells through Raman-DIP. The relative metabolic activity of SCM1 upon exposure to antibiotics was semi-quantitatively calculated based on single-cell Raman spectra. SCM1 exhibited high resistance to erythromycin, tetracycline, novobiocin, neomycin, and vancomycin, with minimum inhibitory concentration (MIC) values between 100 and 400 mg/L, while SCM1 is very sensitive to bacitracin (MIC: 0.8 mg/L). Notably, SCM1 cells were completely inactive under the metabolic activity minimum inhibitory concentration conditions (MA-MIC: 1.6–800 mg/L) for the six antibiotics. Further genomic analysis revealed the antibiotic resistance genes (ARGs) of SCM1, including 14 types categorized into 33 subtypes. This work increases our knowledge of the AMR of marine AOA by linking the resistant phenome to the genome, contributing to the risk assessment of AMR in the underexplored ocean environment. As antibiotic resistance in marine microorganisms is significantly affected by the concentration of antibiotics in coastal environments, we encourage more studies concentrating on both the phenotypic and genotypic antibiotic resistance of marine archaea. This may facilitate a comprehensive evaluation of the capacity of marine microorganisms to spread AMR and the implementation of suitable control measures to protect environmental safety and human health.

Anthropogenically Driven Changes in the Carbon to Phosphorus Ratio of Marine Dissolved Organic Matter

AbstractMarine dissolved organic matter (DOM) cycles play a pivotal role in sustaining marine ecosystems and regulating the ocean's carbon sequestration from the atmosphere. However, the response of DOM cycles, including dissolved organic carbon (DOC) and dissolved organic phosphorus (DOP), to future climate change remains highly uncertain. Using the Community Earth System Model version 2 large ensemble simulations, we find that the C:P ratios in DOM are projected to increase by up to two‐fold in oligotrophic gyres by 2100. Increased upper ocean stratification reduces surface phosphate availability, thereby elevating phytoplankton C:P ratios and enhancing phytoplankton utilization of DOP, both acting to deprive DOM of P. Moreover, ocean stratification has a direct effect on exporting less DOC to the subsurface while accumulating more DOC at the sea surface. As a result of the strong sensitivity to ocean surface warming, the anthropogenically driven trends in upper ocean DOM concentration and its C:P ratios are estimated to emerge earlier from the simulated natural variability than upper ocean phosphate concentrations and net primary production—two key biogeochemical variables that are frequently monitored. This study suggests that changes in the C:P ratios of DOM could serve as a sensitive fingerprint of anthropogenic ocean warming, potentially exerting broad impacts on marine microbes. Our estimated 4% reduction in the globally integrated DOC export below 100 m is comparable to a 2% reduction in particulate organic carbon (POC) export by 2100, implying that global warming is likely to weaken the biological carbon pump through both DOC and POC.

Niche partitioning and plastisphere core microbiomes in the two most plastic polluted zones of the world ocean.

Plastics are offering a new niche for microorganisms colonizing their surface, the so-called "plastisphere," in which diversity and community structure remain to be characterized and compared across ocean pelagic regions. Here, we compared the bacterial diversity of microorganisms living on plastic marine debris (PMD) and the surrounding free-living (FL) and organic particle-attached (PA) lifestyles sampled during the Tara expeditions in two of the most plastic polluted zones in the world ocean, i.e., the North Pacific gyre and the Mediterranean Sea. The 16S rRNA gene sequencing analysis confirmed that PMD are a new anthropogenic ocean habitat for marine microbes at the ocean-basin-scale, with clear niche partitioning compared to FL and PA lifestyles. At an ocean-basin-scale, the composition of the plastisphere communities was mainly driven by environmental selection, rather than polymer types or dispersal effect. A plastisphere "core microbiome" could be identified, mainly dominated by Rhodobacteraceae and Cyanobacteria. Predicted functions indicated the dominance of carbon, nitrogen and sulfur metabolisms on PMD that open new questions on the role of the plastisphere in a large number of important ecological processes in the marine ecosystem.

Global biogeography of microbes driving ocean ecological status under climate change

Microbial communities play a crucial role in ocean ecology and global biogeochemical processes. However, understanding the intricate interactions among diversity, taxonomical composition, functional traits, and how these factors respond to climate change remains a significant challenge. Here, we propose seven distinct ecological statuses by systematically considering the diversity, structure, and biogeochemical potential of the ocean microbiome to delineate their biogeography. Anthropogenic climate change is expected to alter the ecological status of the surface ocean by influencing environmental conditions, particularly nutrient and oxygen contents. Our predictive model, which utilizes machine learning, indicates that the ecological status of approximately 32.44% of the surface ocean may undergo changes from the present to the end of this century, assuming no policy interventions. These changes mainly include poleward shifts in the main taxa, increases in photosynthetic carbon fixation and decreases in nutrient metabolism. However, this proportion can decrease significantly with effective control of greenhouse gas emissions. Our study underscores the urgent necessity for implementing policies to mitigate climate change, particularly from an ecological perspective.

Membraneless channels sieve cations in ammonia-oxidizing marine archaea

Nitrosopumilus maritimus is an ammonia-oxidizing archaeon that is crucial to the global nitrogen cycle1,2. A critical step for nitrogen oxidation is the entrapment of ammonium ions from a dilute marine environment at the cell surface and their subsequent channelling to the cell membrane of N. maritimus. Here we elucidate the structure of the molecular machinery responsible for this process, comprising the surface layer (S-layer), using electron cryotomography and subtomogram averaging from cells. We supplemented our in situ structure of the ammonium-binding S-layer array with a single-particle electron cryomicroscopy structure, revealing detailed features of this immunoglobulin-rich and glycan-decorated S-layer. Biochemical analyses showed strong ammonium binding by the cell surface, which was lost after S-layer disassembly. Sensitive bioinformatic analyses identified similar S-layers in many ammonia-oxidizing archaea, with conserved sequence and structural characteristics. Moreover, molecular simulations and structure determination of ammonium-enriched specimens enabled us to examine the cation-binding properties of the S-layer, revealing how it concentrates ammonium ions on its cell-facing side, effectively acting as a multichannel sieve on the cell membrane. This in situ structural study illuminates the biogeochemically essential process of ammonium binding and channelling, common to many marine microorganisms that are fundamental to the nitrogen cycle.

In situ real-time pathway to study the polyethylene long-term degradation process by a marine fungus through confocal Raman quantitative imaging

Since plastic waste has become a worldwide pollution problem, studying the ability of marine microorganisms to degrade plastic waste is important. However, conventional methods are unable to in situ real-time study the ability of microorganisms to biodegrade plastics. In recent years, Raman spectroscopy has been widely used in the characterization of plastics as well as in the study of biological metabolism due to its low cost, rapidity, label-free, non-destructive, and water-independent features, which provides us with new ideas to address the above limitations. Here, we have established a method to study the degradation ability of microorganisms on plastics using confocal Raman imaging. Alternaria alternata FB1, a recently reported polyethylene (PE) degrading marine fungus, is used as a model to perform a long-term (up to 274 days) in situ real-time nondestructive inspection of its degradation process. We can prove the degradation of PE plastics from the following two aspects, visualization and analysis of the degradation process based on depth imaging and quantification of the degradation rate by crystallinity calculations. The findings also reveal unprecedented degradation details. The method is important for realizing high-throughput screening of microorganisms with potential to degrade plastics and studying the degradation process of plastics in the future.

Harnessing marine microbiomes to develop a sustainable, all-Atlantic bioeconomy.

Harnessing marine microbiomes to develop a sustainable, all-Atlantic bioeconomy.

Exploring the roles of ribosomal peptides in prokaryote-phage interactions through deep learning-enabled metagenome mining

BackgroundMicrobial secondary metabolites play a crucial role in the intricate interactions within the natural environment. Among these metabolites, ribosomally synthesized and post-translationally modified peptides (RiPPs) are becoming a promising source of therapeutic agents due to their structural diversity and functional versatility. However, their biosynthetic capacity and ecological functions remain largely underexplored.ResultsHere, we aim to explore the biosynthetic profile of RiPPs and their potential roles in the interactions between microbes and viruses in the ocean, which encompasses a vast diversity of unique biomes that are rich in interactions and remains chemically underexplored. We first developed TrRiPP to identify RiPPs from ocean metagenomes, a deep learning method that detects RiPP precursors in a hallmark gene-independent manner to overcome the limitations of classic methods in processing highly fragmented metagenomic data. Applying this method to metagenomes from the global ocean microbiome, we uncover a diverse array of previously uncharacterized putative RiPP families with great novelty and diversity. Through correlation analysis based on metatranscriptomic data, we observed a high prevalence of antiphage defense-related and phage-related protein families that were co-expressed with RiPP families. Based on this putative association between RiPPs and phage infection, we constructed an Ocean Virus Database (OVD) and established a RiPP-involving host-phage interaction network through host prediction and co-expression analysis, revealing complex connectivities linking RiPP-encoding prokaryotes, RiPP families, viral protein families, and phages. These findings highlight the potential of RiPP families involved in prokaryote-phage interactions and coevolution, providing insights into their ecological functions in the ocean microbiome.ConclusionsThis study provides a systematic investigation of the biosynthetic potential of RiPPs from the ocean microbiome at a global scale, shedding light on the essential insights into the ecological functions of RiPPs in prokaryote-phage interactions through the integration of deep learning approaches, metatranscriptomic data, and host-phage connectivity. This study serves as a valuable example of exploring the ecological functions of bacterial secondary metabolites, particularly their associations with unexplored microbial interactions.CSrTVep6AzTb_yem78LPYEVideo

Whole-genome sequencing of marine water-derived Curvularia verruculosa KHW-7: a pioneering study

Marine microorganisms are renowned for being a rich source of new secondary metabolites that are significant to humans. The fungi strain KHW-7 was isolated from the seawater collected from the Gulf of Khambhat, India, and identified as Curvularia verruculosa KHW-7. On a next-generation sequencing platform, C. verruculosa KHW-7’s whole-genome sequencing (WGS) and gene annotation were carried out using several bioinformatic methods. The 31.59 MB genome size, 52.3% GC, and 158 bp mean read length were discovered using WGS. This genome also contained 9,745 protein-coding genes, including 852 secreted proteins and 2048 transmembrane proteins. The antiSMASH algorithm used to analyze genomes found 25 secondary metabolite biosynthetic gene clusters (BGCs) that are abundant in terpene, non-ribosomal peptide synthetase (NRPS), and polyketides type 1 (T1PKS). To our knowledge, this is the first whole-genome sequence report of C. verruculosa. The WGS analysis of C. verruculosa KHW-7 indicated that this marine-derived fungus could be an efficient generator of bioactive secondary metabolites and an important industrial enzyme, both of which demand further investigation and development.

Heterotrophic bacteria trigger transcriptome remodelling in the photosynthetic picoeukaryote Micromonas commoda.

Marine biogeochemical cycles are built on interactions between surface ocean microbes, particularly those connecting phytoplankton primary producers to heterotrophic bacteria. Details of these associations are not well understood, especially in the case of direct influences of bacteria on phytoplankton physiology. Here we catalogue how the presence of three marine bacteria (Ruegeria pomeroyi DSS-3, Stenotrophomonas sp. SKA14 and Polaribacter dokdonensis MED152) individually and uniquely impact gene expression of the picoeukaryotic alga Micromonas commoda RCC 299. We find a dramatic transcriptomic remodelling by M. commoda after 8 h in co-culture, followed by an increase in cell numbers by 56 h compared with the axenic cultures. Some aspects of the algal transcriptomic response are conserved across all three bacterial co-cultures, including an unexpected reduction in relative expression of photosynthesis and carbon fixation pathways. Expression differences restricted to a single bacterium are also observed, with the Flavobacteriia P. dokdonensis uniquely eliciting changes in relative expression of algal genes involved in biotin biosynthesis and the acquisition and assimilation of nitrogen. This study reveals that M. commoda has rapid and extensive responses to heterotrophic bacteria in ways that are generalizable, as well as in a taxon specific manner, with implications for the diversity of phytoplankton-bacteria interactions ongoing in the surface ocean.