Mixed fruit wastes as a potential source for Bacteriocin Producing Lactic acid bacterium – Lactobacillus saniviri NKSS1

Abstract

Mixed fruit juices contain microflora on the surface of fruits during the harvest and post-harvest practices. The presence of useful organisms like lactic acid bacteria from the mixed fruit wastes was explored in this study since these microbes use these wastes as a nutrient source for their growth. The lactic acid bacteria isolated using MRS medium was identified as Lactobacillus saniviri NKSS1 by 16s rRNA analysis. The bacteriocin produced by Lactobacillus saniviri NKSS1 showed inhibitory effect against the food pathogen (Listeria monocytogenes) and clinical pathogen (Acinetobacter baumannii). Optimization of bacteriocin production from Lactobacillus saniviri NKSS1 was achieved at 24 h of incubation, temperature at 35 °C with the initial medium pH of 6.5. The carbon & nitrogen sources like dextrose (3% w/v) and yeast extract (0.75% w/v) enhanced the production of bacteriocin in MRS medium. Antimicrobial activity was reduced in the partially purified bacteriocin when incubated at 95 °C for 2 h but it retained its activity in the pH range of 5.5 to 8.5. Whereas, metals like CuSO4 and MgSO4 at (0.5 % w/v) interfered with the antagonistic activity of partially purified bacteriocin. Ionic detergents like SDS and CTAB partially decreased the antimicrobial activity, while other non-ionic detergents inhibited the antimicrobial activity completely. The molecular weight of partially purified bacteriocin from Lactobacillus saniviri NKSS1 was found to be 10.9 kDa. It can be concluded that bacteriocin of L. saniviri NKSS1 holds a promising potential for extension of shelf-life and improvement of microbiological safety in food industries.