Abstract

SCREENING AND CHARACTERIZATION OF NOVEL BACTERIOCIN PRODUCING LACTOBACILLI OBTAINED FROM RAW MILK SAMPLES.

Sarangdhar Mithun*, Vora Dipak and Sarang Sheela.

Abstract

Lactic acid bacteria are known to produce a variety of compounds including bacteriocin, hydrogen peroxide and organic acids which inhibit the growth of spoilage and pathogenic bacteria. Hence they may have potential applications as natural and safe food preservatives. The present study was aimed at isolation and screening of bacteriocin producing lactobacilli from raw milk samples. A total of 73 isolates were obtained from the 10 milk samples procured from a local dairy. Out of these only four of them, two belonging to each L.fermentum and L. viridescens showed promising bacteriocin activity against the test cultures. Maximum activity was obtained against S.aureus, followed by E.coli whereas relatively lower activity was observed against B.subtilis. Upon subsequent heat treatment, the activity of the crude bacteriocin preparations diminished gradually and it was completely destroyed at 100°C. Further, antibiograms were generated for these isolates and MAR index was analyzed. All the isolates were found to be resistant to Penicillin, Norfloxacin and Vancomycin whereas they were found to be sensitive to Bacitracin, Amoxycillin and Ceftazidime. Three of the isolates exhibited a high MAR index greater than 0.2. The bacteriocins obtained from these isolates pose an avenue and may be examined for their potential to replace the conventional synthetic chemicals used in preservation of food.

Keywords: Isolation, Identification, Bacteriocin, Agar Well diffusion, Antibiotic Sensitivity test, MAR Index.