Molecular mechanisms and applications of antimicrobial secondary metabolites of <i>Bacillus subtilis</i> based on biofilm and quorum sensing

ABSTRACT Antimicrobial resistance remains a significant global threat to human health, but microorganisms have long been a crucial source of novel antibiotics. The widely distributed gram-positive bacterium Bacillus subtilis produces an abundance of secondary metabolites, and their antibacterial activities could have significant applications in food, agriculture, and aquaculture areas. These secondary metabolites exert antibacterial effects through mechanisms such as microbial cell membrane structure disruption, cell wall synthesis interference, and cellular metabolic activity inhibition. In contrast to microorganisms such as Streptomyces , B. subtilis forms characteristic biofilms and exhibits quorum sensing, which play important roles in the production of secondary metabolites and their antimicrobial effects. However, limited attention has been focused on the unique molecular mechanisms associated with biofilms and quorum sensing. In this review, we first summarize the typical secondary metabolites produced by B. subtilis . We then mainly focus on the molecular mechanisms associated with the regulation of biofilms and quorum sensing by antimicrobial secondary metabolites, and the effects of biofilms and quorum sensing on the biosynthesis of antimicrobial secondary metabolites. The applications of antimicrobial secondary metabolites in the fields of food, agriculture, and fisheries, based on the regulation of biofilm and quorum sensing, are also summarized. Finally, we highlight the need for further research into the regulatory networks related to biofilms, quorum sensing, and metabolites to facilitate a deeper understanding of the antimicrobial properties of B. subtilis , which may provide theoretical support for the development of novel antimicrobial food technologies.