Microorganisms are widely distributed in food and contribute to food safety due to production of
antagonistic substances. A new bacterial strain, OSY-7LA, was isolated from a Chinese delicacy food and
exhibited strong antagonistic activity against Listeria innocua. It was identified as Bacillus atrophaeus by
morphological, physiological, and biochemical properties and genetic relatedness. The culture supernatant
has antimicrobial activities against the Gram-positive pathogens tested, namely, Listeria monocytogenes,
Bacillus cereus and methicillin-resistant Staphylococcus aureus. The antimicrobial agents were
harvested by solvent extraction and were purified by high performance liquid chromatography (HPLC).