GC-MS Based Metabolomic Profiling of Streptomyces clavuligerus Isolated from Ocimum gratissimum Rhizosphere

Streptomyces clavuligerus is a member of the Actinobacteria family primarily known for its production of clavulanic acid antibiotic. The need for identification of new antimicrobials led to the identification of volatile components of S. clavuligerus metabolites using GC-MS. The isolate was obtained from Ocimum gratissimum rhizosphere using starch casein agar, and identified using molecular typing. The preliminary antibacterial screening of the isolate was carried out using some indicator bacteria from wound sites and urinary tract infection. Its bioactive metabolites were obtained using sub-merged fermentation over a four-day period, and the volatile compounds identified using GC-MS. The organism showed significant (p<0.05) inhibition on Pseudomonas aeruginosa and Escherichia coli. Metabolomics study revealed the presence of compounds of alkanone and alkene functional groups. Eicosene was the major antimicrobial compound identified. Likewise, a non-antimicrobial, steroidal metabolite – pregnelonone, was also dominant in the metabolite mixture produced by the organism. Identifying volatile constituents of microbial metabolites may be a route for obtaining new antimicrobials and the GC-MS is a useful tool for achieving such aim.