Assessment of Bacillus cereus spoilage potential and the antibacterial mechanism of Larimichthys crocea-derived peptide SDH73 against Bacillus cereus

This study investigated the spoilage bacteria associated with Larimichthys crocea (L. crocea) and the potential inhibitory effects of a derived peptide. Spoilage bacteria were isolated and identified using traditional culture methods combined with 16S rDNA sequencing. The results identified Bacillus cereus (B. cereus) as the dominant spoilage bacterium in L. crocea. Ultra-high performance liquid chromatography-mass spectrometry was used to identify small peptides from L. crocea, and bioinformatics methods were employed to screen for peptides with potential inhibitory activity. Among the identified peptides, SDH73 (KRGMLENCILLSLFAK) exhibited significant antibacterial activity, with a minimum inhibitory concentration of 31.25 μg/mL and a minimum bactericidal concentration of 62.50 μg/mL. Through a combination of experimental studies and molecular dynamics (MD) simulations on the interaction between SDH73 and bacterial cell membranes, it was demonstrated that SDH73 disrupted the permeability and integrity of the B. cereus cell membrane, leading to internal structural damage. After penetrating the cell membrane, SDH73 bound to bacterial DNA by inserting it into base pairs, causing structural disruption. Additionally, SDH73 induced apoptosis-like programmed cell death in B. cereus. Furthermore, SDH73 effectively inhibited the growth of B. cereus in sterile fish meat. In conclusion, this study preliminarily revealed the spoilage potential of B. cereus in fish meat and investigated the antibacterial mechanism of the antimicrobial peptide SDH73. The findings provide a scientific basis for the development and application of SDH73 as a novel antimicrobial agent.