BIO-PROFILING OF A POTENTIAL ANTIMYCOBACTERIAL BACTERIOCIN PRODUCED BY BACILLUS SUBTILIS (MK733983) OF ETHNOMEDICINAL ORIGIN

Abstract

Antibiotic resistance is a global crisis and antimicrobial peptides or bacteriocins are the ascending alternatives. This study is reporting a potential bacteriocin from B. subtilis (MK733983) of ethnomedicinal origin showing significant activity with Mycobacterium smegmatis as an indicator organism on spot-on-lawn assay. Production optimization with suitable physical parameters such as modified lysogeny broth [1.5% peptone; 0.75% salt; 0.75% yeast], temperature [35 °C], pH [7], inoculum size [1%] and time course [24 h] has enhanced the activity up to 20%. This study also observed that supplements like minimal essential medium amino acids and B complex vitamins individually has further enhanced the bacteriocin activity by 13% (total 33%), biomass by 43%, total protein and activity by 17% and 22% respectively. However, addition of some common growth supplements like multivitamins with trace elements, CaCl2 and MgSO4 had shown inhibitory effect on bacteriocin activity. Molecular weight of the bacteriocin was estimated to be below 14kDa and bioassay guided TLC techniques showed distinctive antibacterial activity. The bacteriocin completely lost its activity with Trypsin, α-Chymotrypsin, Proteinase K but not with Amylase, and showed up to 40% activity with Papain. It showed heat stability up to 70°C with a wide antibacterial spectrum against standard strains of Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli and Chromobacterium violaceum with minimal inhibitory concentrations ranging between 0.325±0.02-0.75±0.02mg/mL, suggesting the bacteriocin may have wide application prospects.