IN VITRO ANTIMICROBIAL ACTIVITY, OPTIMIZATION OF BIOACTIVE SECONDARY METABOLITES AND MOLECULAR CHARACTERIZATION OF BACILLUS SUBTILIS ISOLATED FROM SOILS OF WESTERN GHATS, INDIA

Abstract

Low molecular mass of secondary metabolites was usually produced from microbes during their late growth phase. They are of huge importance in terms of human health. In this regard, soil samples were collected from Nilgiris district in Western Ghats of Tamil Nadu, India to isolate bioactive potential bacteria. A total of 76 pure bacterial cultures were isolated by serial dilution method and the isolates were initially differentiated based on morphological and staining characteristics. Among these isolates Bacillus subtilis, the identity of which was confirmed by 16S rRNA analysis, showed strong antimicrobial activity against the tested pathogens compared with other strains. Optimization studies revealed that the highest antibiotic production was obtained from fermentation broth medium. Parameters of the culture revealed that 5 days of incubation at 30^oC with pH 8.0 of the production medium exhibited maximum yield. The Minimum Inhibitory Concentration (MIC) and minimum bactericidal and fungicidal concentrations (MBC/MFC) were also determined against all tested pathogens.