ISOLATION AND CHARACTERIZATION OF MICROBES PRODUCING BACTERIOCIN FROM CURD, RAW MILK AND SOIL AND ITS PRESERVATIVE EFFECTS

Bacteriocins are proteinaceous substance produced by bacteria to inhibit the growth of similar or closely related bacterial strains. They are typically considered to be narrow spectrum antibiotics produced by both gram negative and gram positive range of bacteria which possess antimicrobial properties and inhibitory towards sensitive strains. Bacterocins are safer than antibiotic. They can be used from natural material (probiotics). Bacteriocins of lactic acid bacteria are considered as safe natural preservatives or bio preservatives. A total of nineteen colonies were picked from the various samples i.e. Curd, Condensed milk, Soil and Raw milk. All were subjected to bacteriocin assay and a total of six (6) strains showing relative positive results were selected and subjected for further characterization. Among all six (6) isolates (P1, R3, R6, R7, R8, T7), P1and R7 strains showed promising results against various test organisms with the observed bacteriocin activity. During preservative studies, addition of cell free bacteriocin extract of P1 strain showed positive result for preservation of raw milk up to 4days without any change in its pH and colour with respect to other strains. The best bacteriocin producing microbe, strain P1 was identified as Paenibacillus lactis which is an ideal strain that can be use further in probiotics studies for higher yielding and enhancement.