Bacteria display social behavior and establish cooperative or competitive interactions in the niches they occupy. The human skin is a densely populated environment where many bacterial species live. Thus, bacterial inhabitants are expected to find a balance in these interactions, which eventually defines their spatial distribution and the composition of our skin microbiota. Unraveling the physiological basis of the interactions between bacterial species in organized environments requires reductionist analyses using functionally relevant species. Here, we study the interaction between two members of our skin microbiota, Bacillus subtilis and Staphylococcus epidermidis. We show that B. subtilis actively responds to the presence of S. epidermidis in its proximity by two strategies: antimicrobial production and development of a subpopulation with migratory response. The initial response of B. subtilis is production of chlorotetain, which degrades the S. epidermidis at the colony level. Next, a subpopulation of B. subtilis motile cells emerges. Remarkably this subpopulation slides towards the remaining S. epidermidis colony and engulfs it. A slow response back from S. epidermidis cells give origin to resistant cells that prevent both attacks from B. subtilis. We hypothesized that this niche conquering and back-down response from B. subtilis and S. epidermidis, respectively, which resembles other conflicts in nature as the ones observed in animals, may play a role in defining the presence of certain bacterial species in the specific microenvironments that these bacteria occupy on our skin.

细菌表现出社会行为，并在它们占据的生态位中建立合作或竞争的相互作用。人体皮肤是一个人口稠密的环境，许多细菌物种生活在那里。因此，细菌居民有望在这些相互作用中找到平衡，这最终决定了它们的空间分布和我们皮肤微生物群的组成。揭示有组织环境中细菌物种之间相互作用的生理基础需要使用功能相关物种的还原论分析。在这里，我们研究了皮肤微生物群的两个成员——枯草芽孢杆菌和表皮葡萄球菌之间的相互作用。我们表明，枯草芽孢杆菌通过两种策略对其附近表皮葡萄球菌的存在做出积极反应：抗菌剂的产生和具有迁移反应的亚群的发育。枯草芽孢杆菌的最初反应是产生氯泰坦，其在菌落水平上降解表皮葡萄球菌。接下来，枯草芽孢杆菌运动细胞亚群出现。值得注意的是，该亚群滑向剩余的表皮葡萄球菌菌落并将其吞没。表皮葡萄球菌细胞缓慢的反应产生了抵抗枯草芽孢杆菌两种攻击的抗性细胞。我们假设，枯草芽孢杆菌和表皮葡萄球菌的这种生态位征服和后退反应，类似于自然界中观察到的其他冲突，如在动物中观察到的冲突，可能在定义特定细菌物种在特定环境中的存在方面发挥作用。这些细菌在我们皮肤上占据的微环境。