Antibacterial Activity of Extracts of Coprinopsis Cinerea, A Coprophilous Fungus Against Multidrug Resistant Nosocomial Pathogens

Abstract

Our study explored Coprinopsis cinerea (C2), a coprophilous basidiomycetous fungus isolated from horse dung to combat beta-lactamase and carbapenamase producing multidrug resistant nosocomial pathogens in vitro. The isolated strain was cultivated under sub-merged fermentation (SmF) and solid-state fermentation (SSF) for 10 days at 30°C and at pH 6 in dark. After the growth period, the extracellular metabolites were extracted using polar and non-polar solvents and the extracts were subjected for antibacterial activity by agar well diffusion, microbroth dilution and time-kill kinetics assay. The methanolic extract of fruit bodies and mycelial biomass of C. cinerea (C2) grown under wheat flour agar and wheat flour broth respectively, showed significant antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and carbapenamase producing Klebsiella pneumoniae with a zone of inhibition ranging between 10 and 14 mm in diameter. On the contrary, ethyl acetate seems to be the effective solvent for extraction of antimicrobial compounds from culture filtrate of Smf and SSF grown C. cinerea (C2). Among the solid substrates (agrowaste materials), wheat bran supported maximum growth and antimicrobial metabolite production with a significant zone of inhibition ranging between 20 and 22 mm. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ethyl acetate extract of C. cinerea (C2) culture filtrate was 3.12-12.5 mg/mL and 6.25-25 mg/mL, respectively. The time-kill kinetics assay showed the extracted metabolites of culture filtrate was bactericidal in nature.