Secondary metabolites of impact the assembly of soil-derived semisynthetic bacterial communities.

Secondary metabolites provide 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 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 semisynthetic mock communities containing 13 main genera and supplemented them with P5_B1 WT, the NRP-deficient strain , or single-NRP mutants incapable of producing surfactin, plipastatin, or bacillaene. Through 16S amplicon sequencing, it was revealed that the invasion of NRP-producing strains had no major impact on the bacterial communities. Still, the abundance of the two genera and was reduced. Interestingly, this effect was diminished in communities supplemented with the NRP-deficient strain. Growth profiling of M5 exposed to either spent media of the strains or pure surfactin indicated the sensitivity of this strain towards the biosurfactant surfactin. Our study provides a more in-depth insight into the influence of NRPs on semisynthetic bacterial communities and helps to understand their ecological role.