Biology subjects

Grossart, H.-P.

Publications and source records attributed to Grossart, H.-P..

At least 19 recordsLinked to original sources

bioRxiv2026

Exploring Warming Effects on lower food-web dynamics in the plankton of the River Elbe Estuarine Ecosystem in summer: Insights from a Mesocosm Experiment

Understanding how warming alters estuarine plankton communities is essential for predicting future changes in biodiversity and ecosystem functioning. We conducted a four-week indoor mesocosm experiment using natural summer plankton from the Elbe River to examine the effects of warming (+2 {degrees}C and +4 {degrees}C) on abiotic conditions and responses of the plankton community. In this study, oxygen concentrations, primary producer biomass (chlorophyll a, microphytoplankton) and microzooplankton abundances declined sharply during the first 10 days across all treatments while mesozooplankton abundances increased. This suggests a strong top-down control by mesozooplankton on lower trophic levels across all temperature treatments. Primary producers biomass and oxygen concentrations recovered after an initial decline, however to lower levels compared to the onset of the experiment while micro- and mesozooplankton remained low during the second half of the experiment. Nutrient dynamics indicated progressive remineralization, with increasing ammonium, NOx, and silicate concentrations, while phosphate concentrations remained low throughout the experiment. Complementary DNA and RNA metabarcoding revealed similar community turnover over time in all treatments and temperature effects became only pronounced at the end of the experiment. Overall, warming effects were subtle relative to the strong internal trophic dynamics likely caused by the artificial mesocosm setup. Our findings of changes in plankton community dynamics indicate that biotic interactions, changes in trophic diversity and other environmental factors, i.e. oxygen concentrations are likely the drivers of this estuarine system rather than warming alone.

ecology↗

bioRxiv2025

Biological insights and methodological challenges learned from working with a diverse heterotrophic marine bacterial library

BackgroundOrganized collections of bacterial strains can help bridge the gap between studying model organisms and communities, through comparative experiments between genetically and phenotypically diverse strains. We describe the establishment and initial characterization of a library of 62 marine heterotrophic bacteria, selected to represent a significant fraction of the genome-encoded functional diversity and a wide range of known phytoplankton-bacteria interactions. We focus on important but often undiscussed aspects of collecting and maintaining such a library, verifying strain identity, and applying classical microbiological methods across diverse strains. ResultsCultured strains contain up to hundreds of mutations compared with the reference genomes, with non-synonymous mutations in rpoB and/or rpoC genes observed in [~]15% of the cultures. Most strains grow well at 25{degrees}C, but the dependence of growth rate on temperature and the width of the temperature niche vary between strains in a systematic manner. We describe steps towards designing a universal, defined, minimal media for marine bacteria, revealing that growth inhibition on amino acids and peptides by carbohydrates is widespread. Cell counts obtained from flow cytometry and colony plating differ systematically, as do different methods to assess motility. Finally, we discuss traits potentially related to microbial interactions such as hemolysis, biofilm formation, and antibiotic resistance. Gammaproteobacteria such as Alteromonas, Pseudoalteromonas, and Vibrio reveal consistently robust growth, and activity, perhaps explaining why these clades are well-explored. ConclusionExplicitly discussing the insights and challenges of working with strain libraries will pave the way to robust, reproducible, and generalizable mapping of bacterial traits across diversity.

microbiology↗

bioRxiv2024

Suspended and sinking particle-associated microbiomesexhibit distinct lifestyles in the Elbe estuary

Estuaries are important components of the global carbon cycle; exchanging carbon between aquatic, atmospheric, and terrestrial environments, representing important loci for blue carbon storage and greenhouse gas emissions. Estuarine particles are especially important due to their microbial transformation and vertical/horizontal transport. We used metagenomes and metatranscriptomes to assess changes in microbial community composition and functions across the Elbe estuary over one year, linking changes to dissolved and particulate organic matter. We will be the first to link microbial activity derived from molecular data to particulate and dissolved organic carbon characteristics. There were no microbial species responses to the measured physicochemical and dissolved/particulate organic matter parameters, however Weighted Correlation Network Analyses showed significant spatial microbiome differences linked to the estuarine salinity profile. Meanwhile, suspended and sinking particle fractions did not show any community wide differences, but individual gene analyses revealed clear microbial lifestyle differences. Sinking particle-associated transcripts highly expressed competition and stress-responses genes, while suspended particle-associated transcripts favoured energy acquisition and growth. Transcription patterns further indicate that suspended particles may represent a mitigating influence on methane release via methanotrophy, while both suspended and sinking particles produce methane through the same gene complex. This notion suggests that increased sinking particle abundance, such as under high turbidity conditions, leads to increased methane production. Our findings further imply that urban activities such as dredging may have a high impact on greenhouse gas emissions, and higher suspended-sinking particle ratios may alleviate aquatic-atmospheric methane exchanges. Future studies should explore in detail the underlying mechanisms and controlling variables, in particular when taking predicted global changes into account.

ecology↗

bioRxiv2024

Partitioning biota along the Elbe River estuary: where are the community transitions?

Estuarine zonation and community assemblages are frequently correlated with salinity, although the extent or nature of this correlation varies considerably among the published studies. While a smooth transition in biological communities is often conceptualized in association with estuarine fresh, brackish, and marine conditions, many studies have shown more distinct communities and the altogether absence of a brackish community. We explore these viewpoints in light of plant observations and soil and aquatic microbial analyses from permanent plots established on the Elbe River Estuary of northern Germany. Generally, two distinct communities were observed, a polyhaline assemblage towards the mouth of the system, and another that was associated with both the fresh and brackish mesohaline regimes further upriver. This was most pronounced among plant and soil bacteria communities, while aquatic 16S assemblages reflected little distinction at all. The proportion of marine classified taxa declined from the mouth to upriver and suggests that while the transition from marine to brackish or fresh vegetation falls within the sampled area, the same transition for microbial taxa could not be observed and may be further upriver. Thus, although we were able to identify two distinct communities, the "limit" of marine taxa was only evident for vegetation. While tidal and weather-related hydrology, as well as soil properties were also influential in distinguishing the communities, much of the variance remains unexplained. Further sampling, classification, and partitioning is necessary to determine the origin and/or autochthonous habitat, if any, for the Elbe River estuarine taxa. Geographic boundsbottom left: 53.556216{degrees}N, 8.824398{degrees}E top right: 53.917760 {degrees}N, 10.155669 {degrees}E

ecology↗

bioRxiv2024

Effects of excess phosphate on a coastal plankton community

Eutrophication in the Baltic Sea has caused an imbalance in the inorganic nitrogen (N) to phosphorus (P) ratio, leaving excess phosphate (PO4) after the phytoplankton spring bloom that terminates after N-depletion. Using monitoring data, we demonstrated that the PO4 concentration has continued to increase in the outermost Gulf of Finland during past decades. We further investigated the fate of such excess PO4 in a two-week mesocosm (1.2 m3) experiment. The starting concentration of PO4 was 0.66 {micro}M, and treatments included a non-treated control (control), nitrate addition (N-add; 3.6 {micro}M), glucose addition (C-add; 25 {micro}M) and combined nitrate and glucose addition (N+C-add). The addition of N both in N-add and N+C-add treatments stimulated nano- and microphytoplankton, while the picophytoplankton abundance increased only after N-depletion. Also, the copepod biomass was positively affected by the N-addition. N2-fixing cyanobacteria were present but in low abundance. Carbon addition did not enhance heterotrophic bacterial uptake of PO4 contrary to our expectations, nor did it affect the phyto- or zooplankton community composition. The PO4 concentration was reduced to [~]0.4 {micro}M in the control and C-add treatments and to 0.16 {micro}M in the two N-amended treatments, with an inorganic N:P uptake ratio of 6.7. These results underscore the role of picophytoplankton in reducing the excess PO4 pool after the spring bloom, a function traditionally ascribed to bloom-forming diazotrophic cyanobacteria in the Baltic Sea.

microbiology↗

bioRxiv2024

Microbial remineralization processes during post-spring-bloom excess phosphate in the northern Baltic Sea

In the northern Baltic, post-spring-bloom low dissolved inorganic nitrogen to phosphorus conditions, degradation of N-rich organic matter potentially supports the drawdown of excess phosphate. During a 17-day-long mesocosm experiment in the south-west Finnish archipelago, we examined nitrogen, phosphorus and carbon acquiring extracellular enzyme activities in three size fractions (<0.2 {micro}m, 0.2-3 {micro}m, and >3 {micro}m), bacterial abundance, production, community composition and its predicted metabolic functions. The mesocosms received different carbon and nitrogen amendments to test for the effect of inorganic nutrient stoichiometry on enzymatic degradation processes that ultimately determine the export potential of organic matter. Alkaline phosphatase activity occurred mainly in the dissolved form and likely contributed to the excess phosphate conditions. In the beginning of the experiment, peptidolytic and glycolytic enzymes were predicted to be produced by free-living bacteria identified within the classes Actinobacteria and Alphaproteobacteria, whereas the contribution of picocyanobacteria increased towards the end. Our results imply that heterotrophic bacteria lost the competition to picocyanobacteria due to the lack of suitable energy sources. The high hydrolytic rates in fractions <0.2 {micro}m and 0.2-3 {micro}m, found in this study, could potentially retain inorganic nutrients in the surface layer and suppress downward fluxes of organic matter and hence carbon sequestration.

microbiology↗

bioRxiv2023

Virus-encoded Shemin pathway highlights the importance of tetrapyrrole metabolism during host infection

Tetrapyrroles such as heme, chlorophyll, or vitamin B12 are among the most complex molecules synthesised by nature and play a crucial role in many vital processes such as respiration, photosynthesis, methanogenesis, and catalysis. All modified tetrapyrroles are derived from the common precursor molecule 5-aminolevulinic acid (5-ALA). However, 5-ALA can be synthesised in two different ways. While alphaproteobacteria, mammals, and birds use the so-called Shemin pathway, all other bacteria, archaea, and plants use the C5 pathway. Here, we present evidence for the presence of 5-ALA synthase genes of the Shemin pathway in the genomes of viruses (valaS) that infect bacteria (bacteriophages) in marine and freshwater environments. These genes either occur in a three-gene cassette with two heme catabolising enzymes involved in linear tetrapyrrole biosynthesis, as broken cassettes or as individual genes. valaS encodes a functional enzyme, as shown by the enzymatic turnover of the co-substrates succinyl-Coenzyme A and glycine in an Escherichia coli strain overexpressing valaS. Phylogenetic analysis in combination with three-dimensional structure prediction supported our data that the viral sequences encode active enzymes. Interestingly, the viral valaS sequence is capable of functionally complementing a 5-ALA-auxotrophic Escherichia coli strain, which lacks one of the two enzymes of the C5 pathway. Host prediction suggests that different valaS carrying phages might infect bacteria that either utilise the Shemin or the C5 pathway for 5-ALA biosynthesis. Our results thus support the hypothesis that metabolic reprogramming and maintenance of the host bacteriums energy metabolism are crucial during bacteriophage infection and that tetrapyrroles play a key role in this process.

microbiology↗

bioRxiv2023

Phenology and ecological role of Aerobic Anoxygenic Phototrophs in fresh waters

Aerobic anoxygenic phototrophic (AAP) bacteria are heterotrophic bacteria that supply their metabolism with light energy harvested by bacteriochlorophyll-a-containing reaction centres. Despite their substantial contribution to bacterial biomass, microbial food webs and carbon cycle, their phenology in freshwater lakes remains unknown. Hence, we investigated seasonal variations of AAP abundance and community composition biweekly across three years in a temperate, meso-oligotrophic freshwater lake. AAP bacteria displayed a clear seasonal trend with a spring maximum following the bloom of phytoplankton and a secondary maximum in autumn. As the AAP bacteria represent a highly diverse assemblage of species, we followed their seasonal succession using the amplicon sequencing of the pufM marker gene. To enhance the accuracy of the taxonomic assignment, we developed new pufM primers that generate longer amplicons and compiled the currently largest database of pufM gene, comprising 3633 reference sequences spanning all phyla known to contain AAP species. With this novel resource we demonstrated recurrent and dynamic seasonal succession of the AAP community. The majority of the species appeared during specific phases of the seasonal cycle, with less than 2% of AAP species detected during the whole year. Our results document the indigenous freshwater nature of the AAP community, characterized by high resilience and heterogenic adaptations to varying conditions of the freshwater environment. By integrating this information with the indicator of primary production (Chlorophyll-a) and existing ecological models, we show that AAP bacteria play a pivotal role in the recycling of dissolved organic matter released during spring phytoplankton bloom, contributing significantly to the ecological dynamics of lakes.

microbiology↗

bioRxiv2023

Rethinking sinking: Imaging the flow fields of natural marine aggregates to derive sinking velocity

The marine biological carbon pump is mainly driven by the interplay between aggregate sinking velocity and remineralization. Sinking velocity of natural marine aggregates is not routinely measured but often calculated using Stokes law, which does not consider size-dependent changes in porosity. We analyzed the flow fields around 81 in situ-formed aggregates using Particle Image Velocimetry (PIV) to determine the factors controlling aggregate settling. Using an independently derived scaling of porosity with size, we predicted the sinking velocity of laboratory-formed and in situ-formed aggregates with known densities. Small aggregates (<500 {micro}m) have relatively lower porosities than large aggregates, and their increased compactness and density leads to higher size-specific settling velocities, and generally higher carbon-to-volume ratios. Applying our scaling approach to a global data set of vertical aggregate abundance and size distribution, we found that small aggregates contribute 40-70% to total carbon fluxes in situ. TeaserImproved sinking velocity prediction for marine aggregates highlights the contribution of small aggregates to carbon sequestration.

biophysics↗

bioRxiv2023

Phytoplankton tune local pH to actively modulate circadian swimming behavior

Diel vertical migration (DVM), the diurnal exodus of motile phytoplankton between the light- and nutrient-rich aquatic regions, is governed by endogenous biological clocks. Many species exhibit irregular DVM patterns wherein out-of-phase gravitactic swimming-relative to that expected due to the endogenous rhythm-is observed. How cells achieve and control this irregular swimming behavior, and its impact on biological fitness remain poorly understood. Combining local environmental monitoring with behavioral and physiological analyses of motile bloom-forming Heterosigma akashiwo cells, we report that phytoplankton species modulate their DVM pattern by progressively tuning local pH, yielding physiologically equivalent yet behaviorally distinct gravitactic sub-populations which remain separated vertically within a visibly homogeneous cell distribution. Individual and population-scale tracking of the isolated top and bottom sub-populations revealed similar gravitactic (swimming speed and stability) and physiological traits (growth rate and maximum photosynthetic yield), suggesting that the sub-populations emerge due to mutual co-existence. Exposing the top (bottom) sub-population to the spent media of the bottom (top) counterpart recreates the emergent vertical distribution, while no such phenomenon was observed when the sub-populations were exposed to their own spent media. A model of swimming mechanics based on the quantitative analysis of cell morphologies confirms that the emergent sub-populations represent distinct swimming stabilities, resulting from morphological transformations after the cells are exposed to the spent media. Together with the corresponding night-time dataset, we present an integrated picture of the circadian swimming, wherein active chemo-regulation of the local environment underpins motility variations for potential ecological advantages via intraspecific division of labor over the day-night cycle. This chemo-regulated migratory trait offers mechanistic insights into the irregular diel migration, relevant particularly for modelling phytoplankton transport, fitness and adaptation as globally ocean waters see a persistent drop in the mean pH. One sentence summaryActive regulation of local pH diversifies the diel vertical migration of motile phytoplankton.

biophysics↗

bioRxiv2023

Phylogenomics including new sequence data of phytoplankton-infecting chytrids reveals multiple independent lifestyle transitions across the phylum

Parasitism is the most common lifestyle on Earth and has emerged many times independently across the eukaryotic tree of life. It is frequently found among chytrids (Chytridiomycota), which are early-branching unicellular fungi that feed osmotrophically via rhizoids as saprotrophs or parasites. Chytrids are abundant in most aquatic and terrestrial environments and fulfil important ecosystem functions. As parasites, they can have significant impacts on host populations. They cause global amphibian declines and influence the Earths carbon cycle by terminating algal blooms. To date, the evolution of parasitism within the chytrid phylum remains unclear due to the low phylogenetic resolution of rRNA genes for the early diversification of fungi, and because few parasitic lineages have been cultured and genomic data for parasites is scarce. Here, we combine transcriptomics, culture-independent single-cell genomics and a phylogenomic approach to overcome these limitations. We newly sequenced 29 parasitic taxa and combined these with existing data to provide a robust backbone topology for the diversification of Chytridiomycota. Our analyses reveal multiple independent lifestyle transitions between parasitism and saprotrophy among chytrids, multiple host shifts by parasites, and suggest that the chytrid last common ancestor was a parasite of phytoplankton.

evolutionary biology↗

bioRxiv2023

Synergistic effects of predation and parasitism on competition between edible and inedible phytoplankton

Fungi can affect aquatic ecosystems through syntrophic and parasitic interactions with other organisms and organic matter. In pelagic systems, fungal parasites on phytoplankton can control trophic interactions and food-web dynamics, e.g., zooplankton grazing on fungal parasite zoospores creates an alternative energy pathway (termed "mycoloop") from otherwise inedible phytoplankton species. We aim to investigate how the mycoloop influences community dynamics in aquatic food-webs combining experimental and modelling approaches. We assembled an experimental system consisting of an inedible (host) phytoplankton species and its parasitic chytrid, an edible (non-host) phytoplankton species, and a zooplankton grazer. Chytrids parasitizing increased edible phytoplankton abundance, while zooplankton grazing decreased edible phytoplankton abundance. In the presence of zooplankton and chytrids, competition effects between edible and inedible phytoplankton species depended on nutrient levels. At high nutrient levels, competition was balanced by an indirect positive chytrid effect and negative zooplankton grazing effects on edible phytoplankton. In contrast, at low nutrient levels, we found chytrid had a negative impact on edible phytoplankton synergistically with zooplankton. Mathematical investigations suggest that the synergistic effect can be caused by the mycoloop. This indicates that the mycoloop substantially affects predator-prey interactions and phytoplankton competition with yet unknown ecological consequences.

ecology↗

bioRxiv2022

Perchlorate-Specific Proteomic Stress Responses of Debaryomyces hansenii Could Enable Microbial Survival in Martian Brines

If life exists on Mars, it would face several challenges including the presence of perchlorates, which destabilize biomacromolecules by inducing chaotropic stress. However, little is known about perchlorate toxicity for microorganism on the cellular level. Here we present the first proteomic investigation on the perchlorate-specific stress responses of the halotolerant yeast Debaryomyces hansenii and compare these to generally known salt stress adaptations. We found that the responses to NaCl and NaClO4-induced stresses share many common metabolic features, e.g., signaling pathways, elevated energy metabolism, or osmolyte biosynthesis. However, several new perchlorate-specific stress responses could be identified, such as protein glycosylation and cell wall remodulations, presumably in order to stabilize protein structures and the cell envelope. These stress responses would also be relevant for life on Mars, which - given the environmental conditions - likely developed chaotropic defense strategies such as stabilized confirmations of biomacromolecules and the formation of cell clusters.

cell biology↗

bioRxiv2022

From microbes to mammals: pond biodiversity homogenization across different land-use types in an agricultural landscape

Local biodiversity patterns are expected to strongly reflect variation in topography, land use, dispersal boundaries, nutrient supplies, contaminant spread, management practices and other anthropogenic influences. In contrast, studies focusing on specific taxa revealed a biodiversity homogenization effect in areas subjected to long-term intensive industrial agriculture. We investigated whether land use affects biodiversity and metacommunity structure in 67 kettle holes (KH) representing small aquatic islands embedded in the patchwork matrix of a largely agricultural landscape comprising grassland, forest, and arable fields. These KH, similar to millions of standing water bodies of glacial origin, spread across northern Europe, Asia, and North America, are physico-chemically diverse, differ in the degree of coupling with their surroundings. We assessed biodiversity patterns of eukaryotes, Bacteria and Archaea in relation to environmental features of the KH, using deep-amplicon-sequencing of eDNA. First, we asked whether deep sequencing of eDNA provides a representative picture of KH biodiversity across the three domains of life. Second, we investigated if and to what extent KH biodiversity is influenced by the surrounding land-use. Our data shows that deep eDNA amplicon sequencing is useful for in-depth assessments of cross-domain biodiversity comprising both micro- and macro-organisms, but, has limitations with respect to single-taxa conservation studies. Using this broad method, we show that sediment eDNA, integrating several years to decades, depicts the history of agricultural land-use intensification. The latter, coupled with landscape wide nutrient enrichment (including by atmospheric deposition), groundwater connectivity between KH and organismal movement in the tight network of ponds, resulted in a biodiversity homogenization in the KH water, levelling off todays detectable differences in KH biodiversity between land-use types.

ecology↗

bioRxiv2022

Significant organic carbon acquisition by Prochlorococcus in the oceans

Marine phytoplankton are responsible for about half of the photosynthesis on Earth. Many are mixotrophs, combining photosynthesis with heterotrophic assimilation of organic carbon but the relative contribution of these two carbon sources is not well quantified. Here, single-cell measurements reveal that Prochlorococcus at the base of the photic zone in the Eastern Mediterranean Sea are obtaining only ~20% of carbon required for growth by photosynthesis. Consistently, laboratory-calibrated evaluations of Prochlorococcus photosynthesis indicate that carbon fixation is systematically too low to support published in situ growth rates in the deep photic layer of the Pacific Ocean. Furthermore, agent-based model simulations show that mixotrophic cells maintain realistic growth rates and populations 10s of meters deeper than obligate photo-autotrophs, deepening the nutricline and Deep Chlorophyll Maximum by ~20 m. Time-series of Prochlorococcus ecotype-abundance from the subtropical North Atlantic and North Pacific suggest that up to 30% of the Prochlorococcus cells live where light intensity is not enough to sustain obligate photo-autotrophic populations during warm, stratified periods. Together, these data and models suggest that mixotrophy underpins the ecological success of a large fraction of the global Prochlorococcus population and its collective genetic diversity.

microbiology↗

bioRxiv2021

Phytoplankton exudates provide full nutrition to a subset of accompanying heterotrophic bacteria via carbon, nitrogen and phosphorus allocation

Marine bacteria rely on phytoplankton exudates as carbon sources (DOCp). Yet, it is unclear to what extent phytoplankton exudates also provide nutrients such as phytoplankton-derived N and P (DONp, DOPp). We address these questions by exudate addition experiments from the ubiquitous pico-cyanobacterium Prochlorococcus to contrasting ecosystems in the Eastern Mediterranean - a coastal and an open-ocean, oligotrophic station. Nutrient addition did not lower the incorporation of exudate DONp, nor did it reduce alkaline phosphatase activity, suggesting that bacterial communities are able to exclusively cover their nitrogen and phosphorus demands with organic forms provided by phytoplankton exudates. Approximately half of the cells in each ecosystem took up detectable amounts of Prochlorococcus-derived C and N, yet based on 16S rRNA sequencing different bacterial genera were responsible for the observed exudate utilization patterns. In the coastal community, several phylotypes of Aureimarina, Psychrosphaera and Glaciecola responded positively to the addition of phytoplankton exudates, whereas phylotypes of Pseudoalteromonas increased and dominated the open ocean communities. Together, our results strongly indicate that phytoplankton exudates provide coastal and open-ocean bacterial communities with organic carbon, nitrogen and phosphorus, and that phytoplankton exudate serve a full-fledged meal for specific members of the accompanying bacterial community in the nutrient-poor eastern Mediterranean.

ecology↗

bioRxiv2020

Microbial drama in four acts - Extreme rain events cause cyclic succession in plankton communities

Highly abundant, small waterbodies contribute substantially to global freshwater shoreline and surface area. They are strongly interlinked with the terrestrial surrounding, thus controlling the flow of energy, nutrients and organisms through the landscape. Disturbance events can have severe consequences for these ecosystems and the entire downstream freshwater network and require more attention in the context of global change-induced increases in weather extremes. Here we show that extreme rain events (floods) cause cyclic successions in microbial communities and the planktonic food web of a small forest pond. We analyzed the dynamics of nutrients and the entire plankton community during two flood events and subsequent quasi-stable conditions. Floods induced a repeated washout of resident organisms and hundred-fold increases in nutrient load. However, within two weeks, the microbial community recovered to a pre-disturbance state through four well-defined succession phases. Reassembly of phyto- and especially zooplankton took considerably longer and displayed both repetitive and adaptive patterns. Release of dissolved nutrients from the pond was associated with inflow rates and state of community recovery, and it returned to pre-disturbance levels earlier than microbial composition. Our study exemplifies extraordinary compositional and functional resilience of small waterbodies and presents the detailed mechanism of the underlying processes.

ecology↗

bioRxiv2020

Comparative whole-genome approach to identify traits underlying microbial interactions

Microbial interactions shape the structure and function of microbial communities with profound consequences for biogeochemical cycles and ecosystem health. Yet, most interaction mechanisms are studied only in model systems and their prevalence is unknown. To systematically explore the functional and interaction potential of sequenced marine bacteria, we developed a new trait-based approach, and applied it to 473 complete genomes (248 genera), representing a significant fraction of marine microbial communities. We identified genome functional clusters (GFCs) which condense bacterial diversity into groups with potentially common ecology and life history. Most GFCs revealed unique combinations of interaction traits, some widely distributed (e.g., antimicrobial activity), others less common (e.g., production of siderophores and phytohormones, biosynthesis and export of specific B vitamins). Specific GFCs, comprising Alpha- and Gammaproteobacteria, are predicted to preferentially interact synergistically and/or antagonistically with bacteria and phytoplankton. Moreover, linked trait clusters (LTCs) identify traits that may have evolved together and point to specific modes of interactions. Our approach translates multidimensional genomic information into an atlas of marine bacteria and their ecosystem functions, relevant for understanding the fundamental rules that govern community assembly and dynamics.

microbiology↗