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.

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (MTb) and is one of the majorcauses of death in the world. One third of the population suffers with TB and there is no potential drug introduced in the past 5 decades. The drugs currently used are ineffective due to the emergence of MDR (Multidrug Resistant Strain), XDR (Extreme Drug Resistant strain) and other co-infections. Hence there is a need for a potent molecule that can inhibit the growth of mycobacterium effectively. The plant kingdom provides a large variety of naturally occurring phytochemicals and other secondary metabolites which are known to be antibacterial. Therefore the present study focuses on screening and identification of potent antimycobacterial plants. Various parts of the plant including leaves are traditionally used for treating a wide spectrum of diseases. In the screening studies of dry leaf (methanolic extracts) of plants from the Western Ghats region gave rise to two potent anti-mycobacterial plants. These plants were identified as TithoniadiversifoliaHemsl.A. Gray(TD) and CouroupitaguianensisAubl. (CG). Both TD and CG plants showed significant anti-mycobacterial activity conducted by well diffusion assay having clearance zone of 15.6 mm and 17.3 mm respectively. These plant extracts were further purified with polar solvents and potential antimycobacterial extracts were tested for their minimum inhibitory concentrations (MICs). The MICs for TD ethyl acetate extract and CG chloroform extract were reported as less than 64µg/ml and 64µg/ml respectively. The entire investigation of anti-mycobacterial study was conducted against Mycobacterium smegmatis whichis a model organism for mycobacterial studies. These results show that both plants contain potent anti-mycobacterial compound(s) that can be further investigated for purification and isolation of bioactive compound which can be useful in the production of novel drugs.