Reducing the use of chemical fertilizers and improving crop salt stress tolerance by acetoin and 2,3-butanediol produced by Bacillus subtilis

Small volatile molecules are considered to play a role in promoting plant growth, with acetoin and 2,3-butanediol being representative examples. In this study, we employed metabolic engineering of Bacillus subtilis to enhance the production of acetoin and 2,3-butanediol, and investigated their effects on the rhizosphere microbiome and metabolic processes of vegetables, aiming to elucidate the mechanisms by which the acetoin and 2,3-butanediol complex promotes plant growth. First, high-yield B. subtilis strains capable of producing acetoin and 2,3-butanediol were obtained through screening and mutagenesis from soil isolates. Starting from these strains, further metabolic engineering strategies were implemented, including the deletion of by-product synthesis pathways, overexpression of biosynthetic genes, and optimization of the TCA cycle. These modifications significantly improved the production levels of acetoin and 2,3-butanediol.