Isolation and refinement of bacteriocin production by Lactobacillus sp., isolated from curd and its repressive action against clinical pathogens.

Abstract

Lactic acid bacteria (LAB) represent probiotic bacteria and have demonstrated positive physiological effects on human health. Lactobacilli are known for their probiotic activities and potential to combat pathogens. This study aimed to investigate the antimicrobial activity of Lactobacillus strains isolated from various sources against pathogenic bacteria, with the objective of identifying potential bacteriocin producers. Bacteriocins have attracted much attention in the field of biopreservation and human therapeutics. The antagonistic activity of L.lactisproduced bacteriocin and nisin was tested against ten clinical pathogens such as Bacillussubtilis, Enterobacter cloacae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhimurium, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus, Candida albicans and Candida glabrata were assessed using agar well diffusion method.In case of concentration 20 µl, the bacteriocin was active against the three bacterial pathogens, K. pneumoniae, P. aeruginosa and S. typhimurium and the fungal pathogens, Candida spp. showing inhibitory zones of 6 mm.The maximum zone of inhibition was shown against S. typhimurium, with inhibitory zone of 10±0.3 mm at 10 µl, 11±0.3 mm at 20 µl and 12±0.2 mm at 30 µl, whereas minimum zone of inhibition exhibited against K. pneumoniae with zones of inhibition falls on 5±0.01 mm at 10 µl, 6±0.02 mm at 20 µl and 8±0.01 mm at 30 µl concentrations. This indicates Lactococcus lactis produced bacteriocin as well as nisin exhibited significant growth inhibition against ten clinical pathogens. Therefore the bacteriocin can be either used as a biopreservative or as an antibiotic to treat clinical pathogens.