Antifungal potential of actinomycete isolate Streptomyces exfoliatus MT9 against wood-rotting fungi

Abstract

An actinomycete isolate, Streptomyces exfoliatus MT9 was assessed for in vitro antagonism against wood-rotting fungi. Strain MT9 showed strong antagonistic activity (ZOI ? 25 mm) towards various tested wood-rotting fungi. Extracellular production of antifungal metabolite(s) including primary and secondary was monitored up to 10 days of submerged fermentation. Antagonist S. exfoliatus MT9 produces fungal cell-wall lytic enzymes, namely chitinase (3.098 U ml-1), b-1,3 glucanase (2.4 U ml-1) and protease (144.0 U ml-1) and also showed antifungal activity towards tested P. chrysosporium MTCC 787 (12.0 mm) and P. placenta MTCC 144 (16.0 mm). Extracellular culture filtrate (ECF) of S. exfoliatus MT9 also exhibited strong antifungal activity (ZOI ≥ 25 mm) towards tested wood-rotting fungi and n-butanol was found to be the suitable solvent for complete extraction of antifungal metabolite(s) from ECF. Reduced antifungal activity of n-butanol extract against P. chrysosporium MTCC 787 (11.00 mm) and P. placenta MTCC 144 (10.00 mm) on ergosterol agar plate, no activity against bacteria and characteristic UV spectra at 224 nm revealed the polyene nature of antifungal metabolite(s) present in the n-butanol extract. A novel actinomycete isolate, S. exfoliatus MT9 is producing antifungal metabolite(s) that makes it suitable for biotechnological processes and has the potential to be used as a bioactive agent for controlling wood-rotting fungi.