SCREENING AND MODULATION OF THE BACTERICIDAL POTENTIAL OF PICKLE-BASED LACTIC ACID BACTERIA AGAINST COMMON NOSOCOMIAL PATHOGENS

Abstract

Fermentation of vegetables is an important process to preserve food. Fermentation is carried out mostly by LAB which are much resistant to salt. Pickles usually contain a variety of LAB which not only improve digestion of fruits and vegetables but also contribute to unique taste by providing components like exopolysaccharides and bacteriocins. The production of bacteriocins by LAB is useful for human body and are beneficial to reduce growth of foodborne pathogens like S. aureus and E. coli etc. LAB have been used in fermented food industry because they improve the taste of product. From different samples of pickles eighteen Lactic Acid Bacteria (LAB) have been isolated in the current work. The isolates were screened on De Mann Rogosa Sharpe agar (MRS). After preliminary morphological and biochemical examination, twelve out of eighteen strains were identified as Lactobacillus species, while four were Streptococcus species. Antibacterial activity of eight bacteriocin-producing Lactic acid bacterial (LAB) strains were tested against three pathogenic bacteria Escherichia coli (E.coli), Bacillus cereus (B.cerus) and Staphylococcus aureus (S.aureus) by using disk diffusion method. Maximum antibacterial activity was observed against B. cereus and least against E. coli. Bradford method was used in order to estimate the protein bacteriocin. The protein content was measured by comparing it with the bovine serum albumin (BSA) as a standard. LAB are beneficial bacteria for human health as these can be used as natural antibacterial tools against common pathogenic bacterial strains involved in different types of deleterious infections