Extraction and purification of an antimicrobial bioactive element from lichen associated Streptomyces olivaceus LEP7 against wound inhabiting microbial pathogens

Abstract

The ever increasing spectrum of microbial disease and emergence of life threatening antibiotic resistant pathogen necessitates more intensive search for microbial antagonistic agents from diverse symbionts and habitats. Lichens from various niches and its associated cohabitates promise derivation of such antimicrobial compounds. In the present study conventionally and genetically identified Streptomyces olivaceus LEP7, one among 36 isolates from tree bark inhabiting lichen Leptogium sp., was assessed for its synthesis of antimicrobial bioactive compounds. Screening of antimicrobial activity was performed as per standard procedures. In vitro production by shake flask culture, solvent based extraction, TLC and GC–MS based separation, purification and identification revealed the presence of cyclopentene, an effective antimicrobial compound against wound inhabiting pathogens.E. coli, P. aeroginosa, S. aureus, Klebsiella sp., Acinetobacter sp., and Candida sp. MIC value of partially purified compound was 7.81 μg/ml against E. coli and P. aeroginosa. In addition, TLC profile of the active extract displayed four different spot with Rf values of 0.64, 0.78, 0.93 and 1.00. This initial lead will add to antimicrobial arsenal on further research. Keywords: Lichen, Streptomyces olivaceus, Antimicrobial activity, Cyclopentene