Ecological Roles of Bacillus Lipopeptides in Mediating Plant–Microbe Interactions and Rhizosphere Community Dynamics

Abstract The plant-beneficial bacterium Bacillus velezensis and related Bacillus species are increasingly recognized as important contributors to plant growth and health, yet the ecological functions of their secondary metabolites in situ remain poorly understood. Here, we investigated how lipopeptides produced by Bacillus species influence plant performance and root-associated microbial communities. Using Arabidopsis thaliana as a model host, we show that bacterial lipopeptides produced during root colonization promote plant growth by enhancing the uptake of essential mineral elements, including magnesium, calcium, iron, and zinc. Transcriptomic analyses revealed that lipopeptides upregulated host genes involved in metal transport and homeostasis in roots, while downregulating negative regulators of metal uptake. The lipopeptide production reshaped the composition of root-associated bacterial communities by increasing the relative abundance of putatively beneficial taxa and altering overall rhizosphere community structure. Functional genes indicated that lipopeptide enrichment was associated with microbial pathways related to metal transport, nutrient acquisition, and stress adaptation, suggesting that lipopeptides modulate both plant and microbial traits relevant to nutrient cycling. These results provide new insight into the ecological roles of B. velezensis-derived metabolites in plant-associated microbiomes and highlight lipopeptides as promising targets for harnessing beneficial plant–microbe interactions in sustainable agriculture.