Isolation_ Purification and Characterization of Bacteriocin Producing Bacteria from Fermented Milk

Abstract

Nowadays, consumers are demanding minimally processed food, ready to eat foods and foods newlinewithout chemical preservatives. There is a need for preservation of food products to extend newlinethe shelf life and also for killing of spoilage bacteria. The food spoilage bacteria are newlinedeveloping resistance against chemical preservatives. These have posed the challenge for newlinenatural way of preservation. Bacteriocin is the molecules, which are natural origin having newlineantimicrobial activity against the bacteria. Commercially nisin is the only preservative used newlinein food industries and the food spoilage bacteria are getting evolved and new strains are newlinespoiling the food products. Commercially there is a demand for bacteriocin producing newlineprobiotic bacteria in food industries. In the present study, traditional fermented milk was used newlinefor isolating bacteriocin producing bacteria and 30 isolates were selected based on different newlinemorphological features. The isolates were subjected to the catalase test and found 10 isolates newlinewere catalase negative. The catalase negative isolates were screened for bacteriocin newlineproduction against the selected indicator organisms. The isolate with the highest newlineantimicrobial activity was named as SC1. The morphological and biochemical tests revealed newlinethat the isolate belongs to the genus Enterococcus. Further, the isolate was identified as Enterococcus casseliflavus MI001 by 16S rDNA analysis and the gene sequence was submitted in NCBI gen bank. The strain E. casseliflavus able to survive in a temperature newlinerange of 15°C to 45°C, pH 2.5 to 6.5 and salt concentration 2%-10%. The strain newlineE. casseliflavus was identified as a probiotic strain and it showed tolerance to both acid and bile salts. The self aggregation ability of the strain was 63.75% and high co-aggregation ability was found with S.aureus and E. coli. . The optimal conditions for bacteriocin newlineproduction are temperature 35°C and pH 6.5.