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Controlling the growth of food-borne pathogens in foodstuffs is important to enhance food safety and promote higher food safety standards. A number of naturally occurring compounds (e.g., bacteriocins and plant-derived compounds) have been widely reported to be safe and effective antimicrobial agents against spoilage and food-borne pathogenic bacteria. The aim of the present work was to evaluate the antibacterial potential of a semi-purified preparation (SPP) containing bacteriocin from Bacillus velezensis BUU004, a mixture of lemongrass (Cymbopogon citratus (DC) Stapf.), chili spur pepper (Capsicum frutescens L.) extracts, and their combination to control the growth of Escherichia coli and Salmonella Typhimurium in dried, crushed, and seasoned squid during 28 d of storage. The mixed herb extracts (160 mg/mL) showed stronger inhibitory activity against E. coli and S. Typhimurium than the SPP (800 AU/mL) from B. velezensis BUU004. Interestingly, the combination of SPP from B. velezensis BUU004 and the mixed herb extracts substantially decreased the numbers of both pathogens in dried seasoned squid during storage as compared to that observed with the individual additives. The bactericidal activity of the SPP from B. velezensis BUU004 in combination with the mixed herb extracts against the food-borne pathogens involved cell lysis as ruptured cell walls were observed by a scanning electron microscopy. Therefore, the SPP from B. velezensis BUU004 combined with the mixed herb extracts offers tremendous advantages as a novel, safe, natural, and effective way to improve the biosafety of dried seafood products. [ABSTRACT FROM AUTHOR]

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]