Antimicrobial Activity of Bacteriocins Isolated from Lactic Acid Bacteria Against Resistant Pathogenic Strains

摘要

This study was carried out to treat the microbial diseases in natural way and reduced the antibiotic resistance pressure. Five species of Lactic acid bacteria namely, L. acidophilus, L. bulgaricus, L. dulbrueckii L. plantarum, and L. fermentum, were isolated from locally produced yogurt. Bacteriocins were isolated from MRS broth culture of theses Lactic acid bacteria through the ammonium sulphate precipitation method. Extracted bacteriocins were tested against test strain i.e E.coli ATCC 25922 to obtain optimum pH, storage temperature and heating temperature for maximum antibacterial activity. For this (2-12) pH range, storage temperatures (-20℃, 4℃ and 37℃ for 1 month) and heating temperatures (60℃, 100℃ and 121℃ for 15 minutes) were tested. Later the antibacterial activity of these bacteriocins were tested at concluded optimum conditions against each other as well as against different locally isolated pathogens viz. Methicillin-Resistant-Staphylococcus-aureus, E.coli, Salmonella and Staphylococcus aureus by using well diffusion agar method. It was found that bacteriocins activities were maximum at pH 6 and 4℃ storage temperature. Maximum activity was found after heating bacteriocins at 60℃ as compared to 100℃ and 121℃. Bacteriocins of lactobacilli were harmless against each other at any pH, heat temperatures and storage temperatures. Antibacterial activity of bacteriocins extracted from L.acidophilus showed maximum activity against pathogenic bacteria as compare to others. The present study has highlighted the antibacterial role of bacteriocins isolated from Lactic acid bacteria by indicating their potential to treat a variety of human and animal diseases.