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 semisynthetic mock communities containing 13 main genera and supplemented them with B. subtilis P5_B1 WT, the NRP-deficient strain sfp, or single-NRP mutants incapable of producing surfactin, plipastatin, or bacillaene. Through 16S amplicon sequencing, it was revealed that the invasion of NRP-producing B. subtilis strains had no major impact on the bacterial communities. Still, the abundance of the two genera Lysinibacillus and Viridibacillus was reduced. Interestingly, this effect was diminished in communities supplemented with the NRP-deficient strain. Growth profiling of Lysinibacillus fusiformis M5 exposed to either spent media of the B. subtilis 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 B. subtilis NRPs on semisynthetic bacterial communities and helps to understand their ecological role.

中文翻译：

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枯草芽孢杆菌的次生代谢产物影响土壤衍生的半合成细菌群落的组装

次生代谢产物为枯草芽孢杆菌提供了对其他微生物的增强竞争力。特别是，非核糖体肽（NRP）通过引起细胞裂解，真菌膜穿孔，酶抑制或破坏细菌蛋白质合成，具有巨大的抗菌潜力。当枯草芽孢杆菌与其他微生物单一培养物竞争时，这种知识主要是在体外获得的。但是，我们对这些小分子的真正生态作用的理解是有限的。在这项研究中，我们建立了包含13个主要属的土壤半合成模拟群落，并为其补充了枯草芽孢杆菌P5_B1 WT，NRP缺陷菌​​株sfp，或无法产生surfactin，pastastatin或bacillaene的单一NRP突变体。通过16S扩增子测序，发现产生NRP的枯草芽孢杆菌菌株的入侵对细菌群落没有重大影响。尽管如此，Lysinibacillus和Viridibacillus这两个属的丰度降低了。有趣的是，在补充了NRP缺陷菌​​株的社区中，这种影响减弱了。暴露于枯草芽孢杆菌菌株或纯表面活性素的废培养基中的梭状芽孢杆菌M5的生长概况表明该菌株对生物表面活性剂表面活性素的敏感性。我们的研究可以更深入地了解枯草芽孢杆菌NRPs位于半合成细菌群落上，有助于了解其生态作用。