Year: 2026
Type: article
Abstract: Intraspecies interactions shapes microbial community structure and evolution, yet the mechanisms determining competitive outcomes among closely related strains remain unclear. The soil bacterium Bacillus subtilis is a model for microbial social interactions, where quorum-sensing systems regulate cooperation and antagonism. Here, we take a multifaceted approach to dissect the role of quorum-sensing regulation in competitive fitness. Isolate NCIB 3610 carries a signal unresponsive RapP-PhrP module that alters quorum-sensing control and promotes faster growth. Modelling and mutant analysis demonstrate that the small differences in growth rate conferred by RapP-PhrP 3610 are sufficient to drive competitive exclusion. The importance of quorum sensing control is further exemplified by experimental evolution of distinct wild isolates, which revealed recurrent mutations in the sensor kinase comP , which phenocopy complete comP or comA deletions and confer a growth-linked competitive advantage. Key quorum sensing mechanisms are abandoned even in structured microbial communities, where it might be expected that communal traits are favoured. Furthermore, a phylogenomic survey of 370 B. subtilis genomes identified disruptive comP mutations in ∼16% of isolates. However, growth rate alone does not explain all interaction outcomes as even isogenic strains with equivalent doubling times differ in competitiveness. Transcriptomic profiling and validation experiments implicated a type VII secretion system toxin as an additional effector. These findings reveal that disruption of quorum-sensing pathways, whether naturally or through selection, provides a rapid route to competitive advantage, highlighting a fundamental trade-off between communal signalling and individual fitness in microbial populations. Importance Microbial competition and cooperation are key in shaping the structure and evolution of microbial communities. Our study on Bacillus subtilis , a model for microbial social interactions, reveals how alterations in cell-cell communication can enhance competitive fitness. We show, through a combination of modelling, mutational analysis, and experimental evolution, that certain strains of B. subtilis gain competitive advantage by disrupting their quorum sensing pathways, which leads to faster growth and enhanced competitiveness. Such mutations are prevalent in ∼16% of analysed genomes, underscoring their widespread evolutionary benefit under competitive conditions. Our research highlights the delicate balance between individual success and community cooperation in microbes, providing insights into microbial behaviour and potential applications in modifying microbial ecosystems.
Source: PLoS Genetics
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $3,043
Awards: East of Scotland Bioscience Doctoral Training Partnership, Dundee Training Programme in Integrated Molecular, Cellular and Translational Biology, Decoding the biosynthesis machinery and role in host-pathogen interactions of the streptococcal Group A Carbohydrate, Unravelling mechanisms underpinning adaptation in Bacillus subtilis biofilms, Dundee Training Programme in Integrated Molecular, Cellular and Translational Biology, G3423391106, G3468372981, G3787103481, G4134516304, National Biofilms Innovation Centre, G5032741594, G5343221764, UKRI-BBSRC East of Scotland Doctoral Training Partnership 3, G6104719437, Decoding the biosynthesis machinery and role in host-pathogen interactions of the streptococcal Group A Carbohydrate, National Biofilms Innovation Centre, Architecture of a biofilm, G8428595110, G9000197626
OpenAlex ID: W7129549708