DETECTION, OPTIMIZATION AND CHARACTERIZATION OF BACTERIOCIN PRODUCED BY LACTOBACILLUS FERMENTUM A STRAIN ISOLATED FROM HOME MADE CURD- INDIAN TRADITIONAL FOOD

Abstract

Lactic acid bacteria display numerous antimicrobial activities mainly due to the production of bacteriocins and antifungal peptides. Bacteriocins are known for anti-microbial properties against various pathogens. The aim of this work is to investigate the effect of growth conditions on the maximum production of bacteriocin by Lactobacillus fermentum isolated from home made curd. Bacteriocin produced by Lactobacillus fermentum, inhibited the growth of Salmonella typhimurium, Escherichia coli, Staphylococcus aureus, Enterococcus faecalis and Proteus mirabilis. The exponential phase of the growth was started at 4h from the time of incubation. The stationary phase begins at the 12h from the time of incubation. Maximum bacteriocin production of 12650 AU/mL with more biomass was obtained in presence of glucose. Yeast extract as sole nitrogen source, in MRS broth, stimulated bacteriocin production upto 2400 AU/mL. The maximum bacteriocin production of 12200 AU/mL was obtained with 2 % of NaCl. The optimum pH for bacterial growth and bacteriocin production was identified as pH 5. The highest bacteriocin activity of 7250 AU/ml and maximum growth o of 1.90 was recorded at pH 5. Bacteriocin production was found to be highest at 40 C temperature (8100AU/ml). Optimization of bacteriocin production with the modification of environmental growth conditions will greatly benefit efficient commercial applications. The stability of the bacteriocin with respect to pH, temperature, enzyme sensitivity and organic solvents also studied.