Bacillus-derived cyclic lipopeptides modulate microbiome structure and enzymatic activity of soil and increase productivity of potato (Solanum tuberosum L.)

Abstract

Cyclic lipopeptides (CLPs) are well-known secondary metabolites produced by Bacillus bacteria. Current research into the role of lipopeptides in soil microbial ecology suggests that their importance goes beyond the suppression of phytopathogens. Here we studied CLPs (bacillomycins and fengycins) as potential modulators of the structural (taxonomic) and functional (enzymatic activity) properties of the microbiome in agroecosystems with the aim of improving soil health and, consequently, plant productivity. The metabolic activity of the soil microbial communities has been found to be stimulated by the application of CLPs to soil. Microbial enzymes involved in the cycling of carbon (3 enzymes), nitrogen (2 enzymes) and phosphorus (1 enzyme) were activated in an experimental condition. Exposure to CLPs did not alter the alpha diversity of bacteria, but increased the alpha diversity of fungi. Amplicon sequencing showed that the action of CLPs alters the taxonomicstructure of bacterial and fungal communities. The constructed network of relationships between enzyme activity and changes in the microbial community allows us to identify potential taxa of bacteria and fungi that determine the activity of specific enzymes. The proposed mechanism behind changes in soil functional activity involves a change in the abundance of specific groups of bacteria and fungi, which gaine a competitive advantage after the introduction of CLPs into the soil. Finally, we tested the CLPs-based preparation on potato tubers and found that it improved the physiological parameters of the plants. Thus, the use of purified Bacillus-derived CLPs allowed better characterization of the biological effects exerted by soil bacilli on the soil microbiome. Bacillus CLPs are found to be non-toxic and to stimulate soil microbiota.