Characterisation and biosafety evaluation of a novel bacteriocin produced by Bacillus velezensis BUU004.

Development of a novel biopreservative harmless to human health has gained increasing attention to control spoilage and pathogenic bacteria in food products. The aims of the present work were to characterise partially purified substance from Bacillus velezensis BUU004 (PBV), evaluate its cytotoxicity, and assess the presence of encoding genes associated with enterotoxin production in B. velezensis BUU004. The highest antibacterial activity was achieved at 18 h post-incubation in stationary growth phase. The PBV containing bacteriocin displayed proteinaceous nature because its activity was partially inactivated by chymotrypsin and papain, and fully degraded by pepsin, proteinase K and trypsin. Bacteriocin in PBV was thermoresistant up to 96°C, and pH stable ranging from 3.0 - 9.0. It also showed a broad spectrum of antibacterial activity against B. cereus, B. coagulans, Listeria monocytogenes, Micrococcus luteus, Staphylococcus aureus, Escherichia coli, E. coli O157:H7, and Salmonella Typhimurium. The molecular weight of the bacteriocin was approximately 5.75 kDa, and the amino acid sequence revealed 43% similarity with existing antimicrobial peptides as determined by an LC-MS/MS analysis. Furthermore, B. velezensis BUU004 produced the bacteriocin that has a low IC₅₀ of 927.4 µg/mL to HK-2 cells along with absence of enterotoxin genes: cytotoxin K (cytK), hemolysin (hlyII), hemolytic enterotoxin HBL (hblABCD), nonhemolytic enterotoxin NHE (nheABC) and cereulide (cesABCD), indicating its basic biosafety characteristic. Our results suggest that a bacteriocin produced by B. velezensis BUU004 has promising potential as a safe biopreservative in the food industry. [ABSTRACT FROM AUTHOR]