Antibacterial efficacy of nisin, pediocin 34 and enterocin FH99 against Listeria monocytogenes, Enterococcus faecium and bacteriocin cross resistance and antibiotic susceptibility of their bacteriocin resistant variants

The bacteriocin susceptibility of Listeria monocytogenes MTCC 657, Enterococcus faeciumDSMZ 20477, E. faecium VRE, and E. faecalis ATCC 29212 and their corresponding bacteriocin resistant variants was assessed. The single and combined effect of nisin and pediocin 34 and enterocin FH99 bacteriocins produced by Pediococcus pentosaceus 34, and E. faecium FH99, respectively, was determined. Pediocin 34 proved to be more effective in inhibiting L. monocytogenes MTCC 657. A greater antibacterial effect was observed against E. faecium DSMZ 20477 and E. faecium (VRE) when the combination of nisin, pediocin 34 and enterocin FH99 were used whereas in case of L. monocytogenes MTCC 657, a combination of pediocin 34 and enterocin FH99 was more effective in reducing the survival of pathogen. Bacteriocin cross-resistance and the antibiotic susceptibility of wild type and their corresponding resistant variants were assessed and results showed that resistance to a bacteriocin may extend to other bacteriocins within the same class and also the acquired resistance to bacteriocins can modify the antibiotic susceptibility/resistance profile of the bacterial species used in the study. According to the hydrophobicity, nisin resistant variant of L. monocytogenes was more hydrophobic (p < 0.001), whereas the pediocin 34 and enterocin FH99 resistant variants were less hydrophobic than the wild type strain. nisin, pediocin 34 and enterocin FH99 resistant variants of E. faecium DSMZ 20477, and E. faecium VRE were less hydrophobic than their wild type counterparts. Nisin resistant E. faecalis ATCC 29212 was less hydrophobic than its wild type counterpart.   Key words: Nisin, pediocin 34, enterocin 34, Enterococcus, Listeria.