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

<i>Bacillus cereus</i> 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 <i>abrB</i>, 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 <i>lanT</i>, responsible for producing key components of antibacterial activity, is dual-regulated by AbrB. In the Δ<i>abrB</i> strain, five novel AMPs were identified, with MICs ranging from 125 to 250 μg/mL against <i>Corynebacterium glutamicum</i>, 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 <i>Bacillus</i>-derived AMPs regulated by AbrB in <i>B. cereus</i> 0-9.