Isolation and characterization of chitinolytic Streptomyces sp. MT7 and its antagonism towards wood-rotting fungi

Abstract

An actinomycetes isolate of Loktak Lake soil, designated as MT7, was characterized and identified as Streptomyces sp. based on fatty acid methyl ester and 16S ribosomal RNA gene analysis. Streptomyces sp. MT7 showed strong and broad spectrum antagonism towards seven out of eight tested wood-rotting fungi. Strain MT7 secretes three vital fungal cell wall lytic enzymes, i.e. chitinase, β-1,3-glucanase, and protease, and siderophores. Extracellularly produced mycolytic enzymes lost their antifungal activity completely after treatment with proteinase K and heat, indicating that the tested antifungal metabolites are heat-sensitive and proteinaceous in nature. Extracellular fluid (ECF) and its organic solvent extract also exhibited potential antagonism towards the tested wood-rotting fungi. Antifungal metabolites were characterized as polyene in nature. Biocontrol traits like co-production of cell wall lytic enzymes and antifungal secondary metabolites including siderophores by Streptomyces sp. MT7 suggests that it could be employed as a potential biocontrol agent against wood-rotting basidiomycetes.