Biology subjects

Kovacs, A. T.

Publications and source records attributed to Kovacs, A. T..

At least 55 records · Page 3Linked to original sources

bioRxiv2021

Rap-Phr systems in B. subtilis 3610 affect matrix gene expression and play a role in biofilm formation in vitro and on the plant root

Natural isolates of the soil-dwelling bacterium Bacillus subtilis form robust biofilms under laboratory conditions and colonize plant roots. B. subtilis biofilm gene expression displays phenotypic heterogeneity that is influenced by a family of Rap-Phr regulatory systems. Most Rap-Phr systems in B. subtilis have been studied independently, in different genetic backgrounds and under distinct conditions, hampering true comparison of the Rap-Phr systems impact on bacterial differentiation. Here, we investigated each of the 12 Rap-Phr systems of B. subtilis NCIB 3610 for their effect on biofilm formation. By studying single {Delta}rap-phr mutants, we show that despite redundancy between the cell-cell communication systems, deletion of each of the 12 Rap-Phr systems influences matrix gene expression, which could possibly enable fine-tuning of the timing and level of matrix production in response to specific conditions. Furthermore, some of the {Delta}rap-phr mutants demonstrated altered biofilm formation in vitro and colonization of Arabidopsis thaliana roots, but not necessarily similarly in both processes, indicating that the pathways regulating matrix gene expression and other factors important for biofilm formation may be differently regulated under these distinct conditions. Significance StatementNatural isolates of Bacillus subtilis form robust biofilms in vitro and on plant roots. The formation of these heterogeneous populations is regulated by diverse Rap-Phr systems. However, most Rap-Phr systems in B. subtilis have been studied independently and in different genetic backgrounds. Here, we report that all 12 Rap-Phr systems affect matrix gene expression, while some of them affect development of in vitro biofilms and plant root colonization. Our study highlights the importance of the Rap-Phr systems in environmental adaptation of B. subtilis, specifically during biofilm formation in the rhizosphere.

microbiology↗

bioRxiv2021

Diversification of B. subtilis during experimental evolution on A. thaliana leads to synergism in root colonization of evolved subpopulations

The soil bacterium Bacillus subtilis is known to suppress pathogens as well as promote plant growth. However, in order to fully exploit the potential as natural fertilizer, we need a better understanding of the interactions between B. subtilis and plants. Here, B. subtilis was examined for root colonization through experimental evolution on Arabidopsis thaliana. The populations evolved rapidly, improved in root colonization and diversified into three distinct morphotypes. In order to better understand the adaptation that had taken place, single evolved isolates from the final transfer were randomly selected for further characterization, revealing changes in growth and pellicle formation in medium supplemented with plant polysaccharides. Intriguingly, certain evolved isolates showed improved root colonization only on the plant species they evolved on, but not on another plant species, namely tomato, suggesting A. thaliana specific adaption paths. Finally, the mix performed better than the sum of its constituents in monoculture, which was demonstrated to be caused by complementarity effects. Our results suggest, that genetic diversification occurs in an ecological relevant setting on plant roots and proves to be a stable strategy for root colonization. Significance StatementUnderstanding how plant-growth-promoting rhizobacteria (PGPR) colonize plant roots is crucial to fully utilize their potential for agricultural applications. Here, we employ experimental evolution of the PGPR Bacillus subtilis on Arabidopsis thaliana to study root colonization. We revealed that evolving populations rapidly improve in root colonization and diversify into distinct morphotypes. Notably, improved root colonization by evolved isolates was observed on A. thaliana, not on tomato. Moreover, isolates of distinct morphotypes interacted during root colonization and the mixture of morphotypes showed higher productivity than predicted. These findings suggest that genetic diversification might be a stable strategy to maximize root colonization.

microbiology↗

bioRxiv2020

Adaptation of Bacillus thuringiensis to plant colonisation affects differentiation and toxicity

Bacillus cereus group (Bacillus cereus sensu lato) has a diverse ecology, including various species that are vertebrate or invertebrate pathogens. Few isolates from the B. cereus group have however been demonstrated to benefit plant growth. Therefore, it is crucial to explore how bacterial development and toxicity evolves during plant colonization. Herein, we investigated Bacillus thuringiensis (Cry-) adaptation to the colonization of Arabidopsis thaliana roots, and monitored changes in cellular differentiation in experimentally evolved isolates. Isolates from two populations displayed improved iterative ecesis on roots and increased toxicity against insect larvae. Molecular dissection and recreation of a causative mutation revealed the importance of a non-sense mutation in the rho transcription terminator gene. Transcriptome analysis revealed how Rho impacts various B. thuringiensis genes involved in carbohydrate metabolism and virulence. Our work suggests that evolved multicellular aggregates have a fitness advantage over single cells when colonizing plants, creating a trade-off between swimming and multicellularity in evolved lineages, in addition to unrelated alterations in pathogenicity. ImportanceBiologicals-based plant protection relies on the use of safe microbial strains. During application of biologicals to the rhizosphere, microbes adapt to the niche, including genetic mutations shaping the physiology of the cells. Here, the experimental evolution of Bacillus thuringiensis lacking the insecticide crystal toxins was examined on the plant root to reveal how adaptation shapes the differentiation of this bacterium. Interestingly, evolution of certain linages led to increased emetic toxin production, hemolysis and insect larvae pathogenesis in B. thuringiensis driven by transcriptional rewiring. Further, our detailed study reveals how inactivation of the transcription termination protein Rho promotes aggregation on the plant root in addition to altered differentiation and pathogenesis in B. thuringiensis.

microbiology↗

bioRxiv2020

Phylogenetic distribution of secondary metabolites in the Bacillus subtilis species complex

Microbes produce a plethora of secondary metabolites that although not essential for primary metabolism benefit them to survive in the environment, communicate, and influence differentiation. Biosynthetic gene clusters (BGCs) responsible for the production of these secondary metabolites are readily identifiable on the genome sequence of bacteria. Understanding the phylogeny and distribution of BGCs helps us to predict natural product synthesis ability of new isolates. Here, we examined the inter- and intraspecies patterns of absence/presence for all BGCs identified with antiSMASH 5.0 in 310 genomes from the B. subtilis group and assigned them to defined gene cluster families (GCFs). This allowed us to establish patterns in distribution for both known and unknown products. Further, we analyzed variations in the BGC structure of particular families encoding for natural products such as plipastatin, fengycin, iturin, mycosubtilin and bacillomycin. Our detailed analysis revealed multiple GCFs that are species or clade specific and few others that are scattered within or between species, which will guide exploration of the chemodiversity within the B. subtilis group. Uniquely, we discovered that partial deletion of BGCs and frameshift mutations in selected biosynthetic genes are conserved within phylogenetically related isolates, although isolated from around the globe. Our results highlight the importance of detailed analysis of BGCs and the remarkable phylogenetically conserved errodation of secondary metabolite biosynthetic potential in the B. subtilis group. IMPORTANCEMembers of the B. subtilis species complex are commonly recognized producers of secondary metabolites, among those the production of antifungals makes them promising biocontrol strains. However, while there are studies examining the distribution of well-known B. subtilis metabolites, this has not yet been systematically reported for the group. Here, we report the complete biosynthetic potential within the Bacillus subtilis group species to explore the distribution of the biosynthetic gene clusters and to provide an exhaustive phylogenetic conservation of secondary metabolite production supporting the chemodiversity of Bacilli. We identify that certain gene clusters acquired deletions of genes and particular frame-shift mutations rendering them inactive for secondary metabolite biosynthesis, a conserved genetic trait within phylogenetically conserved clades of certain species. The overview presented will superbly guide assigning the secondary metabolite production potential of newly isolated strains based on genome sequence and phylogenetic relatedness.

bioinformatics↗

bioRxiv2020

Phages weaponize their bacteria with biosynthetic gene clusters

Bacteria produce many different specialized metabolites, which are encoded by biosynthetic gene clusters (BGCs). Despite high industrial relevance owing to broad bioactive potential of these metabolites, their ecological roles remain largely unexplored. We analyze all available genomes for BGCs of phage origin. The BGCs predominantly reside within temperate phages infecting certain commensal and pathogenic bacteria. Nearly all phage BGCs encode bacteriocins, which appear to serve as a strong proxy for phage specificity. Using the gut-associated bacterium Bacillus subtilis, we demonstrate how a temperate phage equips its host with a functional BGC, providing it with a competitive fitness advantage over close relatives. Therefore, certain temperate phages use BGCs to weaponize their bacteria against close relatives, leading to evolutionary benefits from lysogeny to the infected host, and hence, to the phage itself. Our study is a large step towards understanding the natural role of specialized metabolites, as well as mutualistic phage-host relationships.

microbiology↗

bioRxiv2020

Impact of Rap-Phr system abundance on adaptation of Bacillus subtilis

Microbes commonly display great genetic plasticity, which has allowed them to colonize all ecological niches on Earth. Bacillus subtilis is a soil-dwelling organism that can be isolated from a wide variety of environments. An interesting characteristic of this bacterium is its ability to form biofilms that display complex heterogeneity: individual, clonal cells develop diverse phenotypes in response to different environmental conditions within the biofilm. Here, we scrutinized the impact that the number and variety of the Rap-Phr family of regulators and cell-cell communication modules of B. subtilis has on genetic adaptation and evolution. We examine how the Rap family of phosphatase regulators impacts sporulation in diverse niches using a library of single and double rap-phr mutants in competition under 4 distinct growth conditions. Using specific DNA barcodes and whole-genome sequencing, population dynamics were followed, revealing the impact of individual Rap phosphatases and arising mutations on the adaptability of B. subtilis.

microbiology↗

bioRxiv2020

Secondary metabolites of Bacillus subtilis impact soil-derived semi-synthetic bacterial community assembly

Secondary metabolites provide Bacillus subtilis with increased competitiveness towards other microorganisms. In particular nonribosomal peptides (NRPs) have an enormous antimicrobial potential by causing cell lysis, perforation of fungal membranes, enzyme inhibition or disruption of bacterial protein synthesis. This knowledge was primarily acquired in vitro when B. subtilis was competing with other microbial monocultures. However, our understanding of the true ecological role of these small molecules is limited. In this study, we have established soil-derived semi-synthetic mock communities containing 13 main genera and supplemented them with B. subtilis P5_B1 WT, its NRP deficient strain sfp or single NRP mutants incapable of producing surfactin, plipastatin or bacillaene. 16S amplicon sequencing revealed that the invasion of NRP-producing B. subtilis strains had no major impact on the bacterial communities. Still, the abundances of the two genera Lysinibacillus and Viridibacillus were reduced. Interestingly, this effect was diminished in communities supplemented with the NRPs deficient strain. Growth profiling of Lysinibacillus fusiformis M5 exposed to either spent media of the B. subtilis strains or pure surfactin indicates the sensitivity of this strain towards the biosurfactant surfactin. Our study provides a more in-depth insight into the influence of B. subtilis NRPs on semi-synthetic bacterial communities and helps to understand their ecological role.

microbiology↗

bioRxiv2020

Genomic and chemical diversity of Bacillus subtilis secondary metabolites against plant pathogenic fungi

Bacillus subtilis produces a wide range of secondary metabolites providing diverse plant-growth-promoting and biocontrol abilities. These secondary metabolites include non-ribosomal peptides (NRPs) with strong antimicrobial properties, causing either cell lysis, pore formation in fungal membranes, inhibition of certain enzymes, or bacterial protein synthesis. However, the natural products of B. subtilis are mostly studied either in laboratory strains or in individual isolates and therefore, a comparative overview of B. subtilis secondary metabolites is missing. In this study, we have isolated 23 B. subtilis strains from eleven sampling sites, compared the fungal inhibition profiles of wild types and their NRPs mutants, followed the production of targeted lipopeptides, and determined the complete genomes of 13 soil isolates. We discovered that non-ribosomal peptide production varied among B. subtilis strains co-isolated from the same soil samples. In vitro antagonism assays revealed that biocontrol properties depend on the targeted plant pathogenic fungus and the tested B. subtilis isolate. While plipastatin alone is sufficient to inhibit Fusarium sp., a combination of plipastatin and surfactin is required to hinder the growth of Botrytis cinerea. Detailed genomic analysis revealed that altered NRP production profiles in certain isolates is due to missing core genes, nonsense mutation, or potentially altered gene regulation. Our study combines microbiological antagonism assays with chemical NRPs detection and biosynthetic gene cluster predictions in diverse B. subtilis soil isolates to provide a broader overview of the secondary metabolite chemodiversity of B. subtilis. IMPORTANCESecondary or specialized metabolites with antimicrobial activities define the biocontrol properties of microorganisms. Members of the Bacillus genus produce a plethora of secondary metabolites, of which non-ribosomally produced lipopeptides in particular display strong antifungal activity. To facilitate prediction of the biocontrol potential of new Bacillus subtilis isolates, we have explored the in vitro antifungal inhibitory profiles of recent B. subtilis isolates, combined with analytical natural product chemistry, mutational analysis, and detailed genome analysis of biosynthetic gene clusters. Such a comparative analysis helped to explain why selected B. subtilis isolates lack production of certain secondary metabolites.

microbiology↗

bioRxiv2020

Phage recombination drives evolution of spore-forming Bacilli

Phages are the main source of within-species bacterial diversity and drivers of horizontal gene transfer, but we know little about the mechanisms that drive genetic diversity of these mobile genetic elements (MGEs). Recently, we showed that a sporulation selection regime promotes evolutionary changes within SP{beta} prophage of Bacillus subtilis, leading to direct antagonistic interactions within the population. Herein, we reveal that under a sporulation selection regime, SP{beta} recombines with low copy number phi3Ts phage DNA present within the B. subtilis population. Recombination results in a new prophage occupying a different integration site, as well as the spontaneous release of virulent phage hybrids. Analysis of Bacillus sp. strains suggests that SP{beta} and phi3T belong to a distinct cluster of unusually large phages inserted into sporulation-related genes that are equipped with a spore-related genetic arsenal. Comparison of Bacillus sp. genomes indicates that similar diversification of SP{beta}-like phages takes place in nature. Our work is a stepping stone toward empirical studies on phage evolution, and understanding the eco-evolutionary relationships between bacteria and their phages. By capturing the first steps of new phage evolution, we reveal striking relationship between survival strategy of bacteria and evolution of their phages.

microbiology↗

bioRxiv2019

Surfactin production is not essential for pellicle and root-associated biofilm development of Bacillus subtilis

Secondary metabolites have an important impact on the biocontrol potential of soil-derived microbes. In addition, various microbe-produced chemicals have been suggested to impact the development and phenotypic differentiation of bacteria, including biofilms. The non-ribosomal synthesized lipopeptide of Bacillus subtilis, surfactin, has been described to impact the plant promoting capacity of the bacterium. Here, we investigated the impact of surfactin production on biofilm formation of B. subtilis using the laboratory model systems; pellicle formation at the air-medium interface and architecturally complex colony development, in addition to plant root-associated biofilms. We found that the production of surfactin by B. subtilis is not essential for pellicle biofilm formation neither in the well-studied strain, NCIB 3610, nor in the newly isolated environmental strains, but lack of surfactin reduces colony expansion. Further, plant root colonization was comparable both in the presence or absence of surfactin synthesis. Our results suggest that surfactin-related biocontrol and plant promotion in B. subtilis strains are independent of biofilm formation.

microbiology↗

bioRxiv2019

Differential equation based minimal model describing metabolic oscillations in Bacillus subtilis biofilms

Biofilms offer an excellent example of ecological interaction among bacteria. Temporal and spatial oscillations in biofilms are an emerging topic. In this paper we describe the metabolic oscillations in Bacillus subtilis biofilms by applying the smallest theoretical chemical reaction system showing Hopf bifurcation proposed by Wilhelm and Heinrich in 1995. The system involves three differential equations and a single bilinear term. We perform computer simulations and a detailed analysis of the system including bifurcation analysis and quasi-steady-state approximation. We also discuss the feedback structure of the system and the correspondence of the simulations to biological observations. We also specifically select parameters that are more suitable for the biological scenario of biofilm oscillations. Our theoretical work suggests potential scenarios about the oscillatory behaviour of biofilms and also serves as an application of a previously described chemical oscillator to a biological system.

systems biology↗

bioRxiv2019

Privatization of biofilm matrix in structurally heterogeneous biofilms

ABSTRACTThe self-produced biofilm provides beneficial protection for the enclosed cells, but the costly production of matrix components makes producer cells susceptible to cheating by non-producing individuals. Despite detrimental effects of non-producers, biofilms can be heterogeneous, with isogenic non-producers being a natural consequence of phenotypic differentiation processes. For instance, in Bacillus subtilis biofilm cells differ in the two major matrix components production, the amyloid fiber protein TasA and exopolysaccharides (EPS), demonstrating different expression levels of corresponding matrix genes. This raises questions regarding matrix gene expression dynamics during biofilm development and the impact of phenotypic non-producers on biofilm robustness. Here, we show that biofilms are structurally heterogeneous and can be separated into strongly and weakly associated clusters. We reveal that spatiotemporal changes in structural heterogeneity correlate with matrix gene expression, with TasA playing a key role in biofilm integrity and timing of development. We show that the matrix remains partially privatized by the producer subpopulation, where cells tightly stick together even when exposed to shear stress. Our results support previous findings on the existence of ‘weak points’ in seemingly robust biofilms as well as on the key role of linkage proteins in biofilm formation. Furthermore, we provide a starting point for investigating the privatization of common goods within isogenic populations.IMPORTANCE Biofilms are communities of bacteria protected by a self-produced extracellular matrix. The detrimental effects of non-producing individuals on biofilm development raises questions about the dynamics between community members, especially when isogenic non-producers exist within wild-type populations. We asked ourselves whether phenotypic non-producers impact biofilm robustness, and where and when this heterogeneity of matrix gene expression occurs. Based on our results we propose that the matrix remains partly privatized by the producing subpopulation, since producing cells stick together when exposed to shear stress. The important role of linkage proteins in robustness and development of the structurally heterogeneous biofilm provides an entry into studying the privatization of common goods within isogenic populations.Competing Interest StatementThe authors have declared no competing interest.View Full Text

microbiology↗

bioRxiv2019

BiofilmQ, a software tool for quantitative image analysis of microbial biofilm communities

Biofilms are now considered to be the most abundant form of microbial life on Earth, playing critical roles in biogeochemical cycles, agriculture, and health care. Phenotypic and genotypic variations in biofilms generally occur in three-dimensional space and time, and biofilms are therefore often investigated using microscopy. However, the quantitative analysis of microscopy images presents a key obstacle in phenotyping biofilm communities and single-cell heterogeneity inside biofilms. Here, we present BiofilmQ, a comprehensive image cytometry software tool for the automated high-throughput quantification and visualization of 3D and 2D community properties in space and time. Using BiofilmQ does not require prior knowledge of programming or image processing and provides a user-friendly graphical user interface, resulting in editable publication-quality figures. BiofilmQ is designed for handling fluorescence images of any spatially structured microbial community and growth geometry, including microscopic, mesoscopic, macroscopic colonies and aggregates, as well as bacterial biofilms in the context of eukaryotic hosts.

microbiology↗

bioRxiv2019

Fungal hyphae colonization by Bacillus subtilis relies on biofilm matrix components

Bacteria interact with their environment including microbes and higher eukaryotes. The ability of bacteria and fungi to affect each other are defined by various chemical, physical and biological factors. During physical association, bacterial cells can directly attach and settle on the hyphae of various fungal species. Such colonization of mycelia was proposed to be dependent on biofilm formation by the bacteria, but the essentiality of the biofilm matrix was not represented before. Here, we demonstrate that secreted biofilm matrix components of the soil-dwelling bacterium, Bacillus subtilis are essential for the establishment of a dense bacterial population on the hyphae of the filamentous black mold fungus, Aspergillus niger and the basidiomycete mushroom, Agaricus bisporus. We further illustrate that these matrix components can be shared among various mutants highlighting the community shaping impact of biofilm formers on bacteria-fungi interactions.

microbiology↗

bioRxiv2019

Depiction of secondary metabolites and antifungal activity of Bacillus velezensis DTU001

For a safe and sustainable environment, effective microbes as biocontrol agents are in high demand. We have isolated a new Bacillus velezensis strain DTU001, investigated its antifungal spectrum, sequenced its genome, and uncovered the production of lipopeptides in HPLC-HRMS analysis. To test the antifungal efficacy, extracts of B. velezensis DTU001 was tested against a range of twenty human or plant pathogenic fungi. We demonstrate that inhibitory potential of B. velezensis DTU001 against selected fungi is superior in comparison to single lipopeptide, either iturin or fengycin. The isolate showed analogous biofilm formation to other closely related Bacilli. To further support the biocontrol properties of the isolate, coculture with Candida albicans demonstrated that B. velezensis DTU001 exhibited excellent antiproliferation effect against C. albicans. In summary, the described isolate is a potential antifungal agent with a broad antifungal spectrum that might assist our aims to avoid hazardous pathogenic fungi and provide alternative to toxicity caused by chemicals.

microbiology↗

bioRxiv2018

Cheater-mediated evolution shifts phenotypic heterogeneity in Bacillus subtilis biofilms

Biofilms are closely packed cells held and shielded by extracellular matrix composed of structural proteins and exopolysaccharides (EPS). As matrix components are costly to produce and shared within the population, EPS-deficient cells can act as cheaters by gaining benefits from the cooperative nature of EPS producers. Remarkably, genetically programmed EPS producers can also exhibit phenotypic heterogeneity at single cell level. Previous studies have shown that spatial structure of biofilms limits the spread of cheaters, but the long-term influence of cheating on biofilm evolution is not well understood. Here, we examine the influence of EPS non-producers on evolution of matrix production within the populations of EPS producers in a model biofilm-forming bacterium, Bacillus subtilis. We discovered that general adaptation to biofilm lifestyle leads to an increase in phenotypical heterogeneity of eps expression. Apparently, prolonged exposure to EPS-deficient cheaters, may result in different adaptive strategy, where eps expression increases uniformly within the population. We propose a molecular mechanism behind such adaptive strategy and demonstrate how it can benefit the EPS-producers in the presence of cheaters. This study provides additional insights on how biofilms adapt and respond to stress caused by exploitation in long-term scenario.

microbiology↗

bioRxiv2018

Hampered motility promotes the evolution of wrinkly phenotype in Bacillus subtilis

Selection for a certain trait in microbes depends on the genetic background of the strain and the selection pressure of the environmental conditions acting on the cells. In contrast to the sessile state in the biofilm, various bacterial cells employ flagellum-dependent motility under planktonic conditions suggesting that the two phenotypes are mutually exclusive. However, flagellum dependent motility facilitates the prompt establishment of floating biofilms on the air-medium interface, called pellicles. Previously, pellicles of B. subtilis were shown to be preferably established by motile cells, causing a reduced fitness of non-motile derivatives in the presence of the wild type strain. Here, we show that lack of fully assembled flagella promotes the evolution of matrix overproducers that can be distinguished by the characteristic wrinkled colony morphotype. The wrinkly phenotype is associated with amino acid substitutions in the master repressor of biofilm-related genes, SinR. By analyzing one of the mutations, we show that it alters the tetramerization and DNA binding properties of SinR, allowing an increased expression of the operon responsible for exopolysaccharide production. Finally, we demonstrate that the wrinkly phenotype is advantageous when cells lack flagella, but not in the wild type background.\n\nGraphical Abstract\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=194 SRC=\"FIGDIR/small/288951v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (47K):\norg.highwire.dtl.DTLVardef@1a70c4org.highwire.dtl.DTLVardef@1e16453org.highwire.dtl.DTLVardef@819999org.highwire.dtl.DTLVardef@8b2bde_HPS_FORMAT_FIGEXP M_FIG C_FIG Abbreviated SummaryDuring biofilm establishment at the air-liquid interface, Bacillus subtilis evolves matrix overproducers with a wrinkly colony phenotype (WS). This is caused by mutations in the regulator SinR which alter its dimerization and DNA interaction properties. The matrix overproducers appear mostly in a non-motile mutant where they possess a competitive advantage for biofilm formation, which is not present in the wild type background.

microbiology↗

bioRxiv2017

Division of labor during biofilm matrix production

Organisms as simple as bacteria can engage in complex collective actions, such as group motility and fruiting body formation. Some of these actions involve a division of labor, where phenotypically specialized clonal subpopulations, or genetically distinct lineages cooperate with each other by performing complementary tasks. Here, we combine experimental and computational approaches to investigate potential benefits arising from division of labor during biofilm matrix production. We show that both phenotypic and genetic strategies for a division of labor can promote collective biofilm formation in the soil bacterium Bacillus subtilis. In this species, biofilm matrix consists of two major components; EPS and TasA. We observed that clonal groups of B. subtilis phenotypically segregate into three subpopulations composed of matrix non-producers, EPS-producers, and generalists, which produce both EPS and TasA. This incomplete phenotypic specialization was outperformed by a genetic division of labor, where two mutants, engineered as specialists, complemented each other by exchanging EPS and TasA. The relative fitness of the two mutants displayed a negative frequency dependence both in vitro and on plant roots, with strain frequency reaching a stable equilibrium at 30% TasA-producers, corresponding exactly to the population composition where group productivity is maximized. Using individual-based modelling, we show that asymmetries in strain ratio can arise due to differences in the relative benefits that matrix compounds generate for the collective; and that genetic division of labor can be favored when it breaks metabolic constraints associated with the simultaneous production of two matrix components.\n\nHighlights- matrix components EPS and TasA are costly public goods in B. subtilis biofilms\n\n- genetic division of labor using {Delta}eps and {Delta}tasA fosters maximal biofilm productivity\n\n- {Delta}eps and {Delta}tasA cooperation is evolutionary stable in laboratory and ecological systems\n\n- costly metabolic coupling of public goods favors genetic division of labor

microbiology↗