Transcriptomic and metabolomic analyses reveal the antibacterial mechanism of cell wall lytic enzyme LysM15 against Bacillus cereus

Bacillus cereus is a common spoilage microorganism that can survive in various foods and produce toxins, causing food poisoning such as diarrhea and vomiting, and seriously threatening public health and food safety. Therefore, developing efficient and safe control methods is of great significance for ensuring food quality. In this study, we identified and characterized a novel cell wall lytic enzyme, LysM15, derived from the genome of B. cereus VD045. Structural analysis showed that LysM15 contains an M15 catalytic domain and an SH3 binding domain. Recombinant LysM15 exhibited strong and specific lytic activity against B. cereus , with no effect on other pathogenic species, achieving rapid bacterial lysis within 10 min at 0.008 g/L. At 0.0125 g/L, it also effectively inhibited spore germination and eliminated preformed biofilm. Moreover, the enzyme maintained high lytic activity under a variety of physicochemical conditions, including pH 7.0–9.0, 50 °C, and 0.3 mol/L NaCl. Mechanistic investigations showed that LysM15 disrupted the cell wall, caused cytoplasmic leakage and structural collapse, and interfered with metabolism and gene expression, ultimately leading to bacterial death. Notably, LysM15 significantly decreased B. cereus counts in beef samples stored at 4 °C. These findings suggest that LysM15 possesses strong, specific, and stable antibacterial properties, highlighting its potential as an effective biocontrol agent against B. cereus contamination in food systems.