Studies on Antimicrobial Activity of Bacteriocin Against Foodborne Pathogens in Conjunction With Fatty Acids Eugenol and Ferulic Acid

Abstract

Bacteriocins are antimicrobial peptides which can be used as bio preservatives for restricting the growth of food spoilage microorganisms. Optimization of medium ingredients and physico-chemical parameters were carried out to enhance bacteriocin production. The maximum zone of inhibition noticed due to bacteriocin activity using response surface methodology was found to be 23.30±0.173 mm, 1000 AU/ml when the medium was prepared by adding 3.50 % yeast extract and 3.50 % dextrose. A consortium of selected bacterial isolates L. plantarum DFR 4, E. faecalis DFR P1 and E. faecalis DFR4 (31.24±0.33 mm,1374 AU/ml), showed enhanced bacteriocin production when compared to a single culture of L. plantarum DFR 4 (23.34±0.14 mm, 1000 AU/ml). pH ranging from 3.0-5.0 was found to be appropriate for bacteriocin activity from the isolates such as L. plantarum DFR 4, E. faecalis DFR P1 and E. faecalis DFR4, and could withstand higher temperatures such as 80º, 100ºC for 30 minutes and 121ºC for 15 minutes. The yield of bacteriocin was observed to be highest usingcold acetone precipitation (80%) whereas, the percentage fold purification and specific activity was maximum when gel permeation chromatography was used. Bacteriocins were found to be inactivated when treated with proteinase K and papain. However, and#945;-amylase had no effect on bacteriocins. Bacteriocin production using immobilized cells (20.91±0.35 mm, 940 AU/ml) were found to be higher than that of a free cell system (8.52±0.26 mm, 390 AU/ml). Bamboo fibre was used to immobilize selected mixed culture of L. plantarum DFR 4, E. faecalis DFR P1 and E. faecalis DFR4 for achieving enhanced bacteriocin within 24 hours (1450 AU/ml). Bacteriocin obtained from immobilized L. plantarum DFR 4 could preserve the juice up to 17 days while bacteriocins (produced from immobilized selected cocultured bacteria) could preserve up to 26 days at low temperature (5ºC). Combinational treatments of eugenol and ferulic acid with bacteriocin could enhance the efficiency of the bacteriocin and were