RESEARCH ON SELECTION OF LACTIC ACID BACTERIA WITH ABILITY TO PRODUCE HIGH BACTERIOCIN FROM NATURAL FERMENTED PRODUCTS

Abstract

Lactic acid bacteria (LAB) have been found and used in many traditional fermented products in natural conditions. Recent researches have proved that LAB are able to produce bacteriocin (a biological antibiotic with nature of protein). The aim of this study was to isolate and select LAB capable of producing high bacteriocin from natural fermented products. From six natural fermented products, we isolated 14 LAB strains and identified their biological, physiological, and biochemical characteristics. From the isolated strains, we tested the ability of bacteriocin production which is expressed in the antibacterial activity with control bacteria Staphylococcus aureus, 8 of which exhibited positive antibacterial activity (substraction of antibacterial circle diameters greater than 10 mm). From the 8 above strains, we selected SC3 strain having the highest bacteriocin production, showing activity against all tested strains Staphylococcus aureus, E. coli, Samonella with substraction of antibacterial circle diameters ranged from 19.5 to 24 mm. In addition, research has shown that speed of centrifugation to separate biomass and impurities for recovery of crude bacteriocin does not affect the antimicrobial activity but only affect on purity of the product, the centrifuge speed of 13000 rpm is best suitable.