Unraveling Endogenous Antimicrobial Peptides from Bacillus cereus 0–9 Governed by the Global Transcriptional Regulator AbrB

Bacillus cereus 0-9 is a biocontrol strain with abundant antimicrobial peptide (AMP) biosynthesis gene clusters. This strain exhibits significant antibacterial activity against Gram-positive bacteria. Notably, the deletion of gene abrB, encoding global transcriptional regulator AbrB, resulted in a 62.74% increase in the antibacterial efficacy of strain 0-9. EMSA studies revealed that the gene cluster lanT, responsible for producing key components of antibacterial activity, is dual-regulated by AbrB. In the ΔabrB strain, five novel AMPs were identified, with MICs ranging from 125 to 250 μg/mL against Corynebacterium glutamicum, surpassing the antibacterial efficacy of Nisin Z. Furthermore, the presence of K⁺, Ni²⁺, Zn²⁺, and Ca²⁺ ions significantly enhances the antibacterial activity of the peptides TPV21, LLV7, and CPR6. The genes FRY47_03100 and FRY47_15105, which encode precursor proteins associated with LLV7 and CPR6, are also directly regulated by AbrB. This research expands our understanding of Bacillus-derived AMPs regulated by AbrB in B. cereus 0-9.