Abstract

Bacteriocins are of special interest due to their potential value as natural preservative. The present study is a trial for production of such bacteriocin from a marine Lactobacillus sp.Lactic acid bacteria (LBA) was isolated from fish gut (Mugil cephalus) and prawn muscle (Peneaus monodon) samples and their density were found to be 5.2 x 10⁷ and 6.4 x 10⁷CFU/g respectively. Various pathogens were isolated from ready to eat pickle samples (bottled). The LAB strains were tested against 10 different commercial antibiotics. Among them Vancomycin was the only antibiotic that showed a minimum of 40% resistance to the LAB strains tested. LAB strains were optimized at different parameters and maximum bacteriocin production was at pH 6, temperature of 35°C, 3.5% of salt concentration, 24th h of incubation period. Bacteriocin produced by these strains were precipitated from the culture filtrate using methanol and TCA which was further dialyzed, centrifuged and lyophilized. Lactobacillus fermentum was selected as the most potential strain for both bacteriocin production as well as antimicrobial activity. sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis proved that the obtained protein is homologous with a molecular weight of 18 kDa. FT-IR spectrum also confirmed the obtained protein as a bacteriocin. The study revealed that Lactobacillus strains of marine origin are having the potential to be used as biopreservatives especially in seafood industries. The production of bacteriocin from L. fermentum was found to be ideal for industrial scale production and commercial utilization.

Key words: Bacteriocin, Lactobacillus fermentum, biopreservative, fourier transform infrared (FT-IR).