Control of Listeria monocytogenes on sliced bologna sausage using a novel bacteriocin, amysin, produced by Bacillus amyloliquefaciens isolated from Thai shrimp paste (Kapi)

Listeria monocytogenes is a foodborne pathogen causing listeriosis, a disease of great concern due to high fatality rates. Furthermore the bacterium has the ability to survive under stressful conditions. The objectives of this study were to characterize and evaluate the effectiveness of new antilisteria bacteriocin designated as amysin produced by Bacillus amyloliquefaciens strain SP-1-13LM isolated from Thai shrimp paste or “Kapi”. The partially purified bacteriocin or PPB containing amysin prepared from strain SP-1-13LM showed a broad range of inhibition including L. monocytogenes, Salmonella sp. and Shigella sp. It was found that the antimicrobial activity of PPB was heat stable up to 100 °C for 60 min and active within the pH range of 3–9. The activity of PPB disappeared when treated with proteinase K, α-chymotrypsin and trypsin demonstrating its proteinaceous nature. Tris-Tricine SDS-PAGE analysis revealed that amysin prepared from B. amyloliquefaciens strain SP-1-13LM had an apparent molecular weight of 5.2 kDa. PCR analysis revealed the presence of malonyl CoA transacylase (ituD), lichenysin synthetase C (lchAC) and surfactin synthetase (sfp) coding for iturin, lichenysin C and surfactin, respectively. The potent antilisterial effect of amysin on the growth of L. monocytogenes in sliced bologna sausage was observed during seven days of storage at 4 °C. The potential application of amysin, non-nisin bacteriocin, might be exploited as a safe food biopreservative for used with nisin to inhibit all foodborne pathogens and minimize the nisin-resistant problem of L. monocytogenes in the food industry.