Evaluation of bio-preservative potential of bacteriocins extracted from lactobacillus spp

Bacteriocins produced by Lactic Acid Bacteria (LAB) have garnered significant attention for their potential as natural and safe preservatives in the food industries, being Generally Regarded as Safe (GRAS) and typically non-toxic. This study aimed to isolate, partially purify, and characterize bacteriocins from LAB isolated from milk and yogurt samples. Initial screening of bacteriocin producing microbes was performed by agar-overlay method against Staphylococcus sp. Bacteriocin activity assay was performed using agar-well diffusion method against Escherichia Coli, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi by determining their zone of inhibition. The proteinaceous compound was isolated from cell-free culture supernatant and was partially purified by 60% ammonium sulphate precipitation and was further purified by extraction with chloroform-methanol (2:1 v/v), followed by molecular identification using Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS PAGE) and characterization of its stability under various conditions. Finally, the bacteriocin preparation was sprayed on beef sample and was evaluated up to 48 hours. Two of the isolates demonstrated significant antimicrobial activity against all four indicator bacteria. The bacteriocins were stable across various pH levels, temperatures, and proteolytic enzyme treatments. After 12 h, it exhibited significant microbial inhibition (Control: TBC 2.55×108 CFU/g and CC 1.92×106 CFU/g; Sample: TBC 2.2×108 CFU/ml and CC 1.8×106 CFU/ml). Thus, the isolated LAB strains exhibit potential for bacteriocin production, offering promising applications in food preservation and safety, particularly on meat and meat products.