Streptomyces sp.VSMGT1014-Mediated Antifungal Activity Against Fungal Plant Pathogens

Abstract

Presently actinomycetes from rice rhizosphere are screened for novel bioactive secondary metabolites and for biocontrol potential against fungal plant pathogens. A total of 102 actinomycetes were isolated from rice rhizosphere soils collected from Tamil Nadu, India. All the isolates were screened against sheath blight pathogen Rhizoctonia solani by dual culture method with inhibition zone range from 0.6 to 3.0 cm. Among 102, 56 have shown the antagonistic activity against R. solani. Due to superior biocontrol activity against fungal pathogens over the other actinomycetes, an efficient strain VSMGT1014 was selected and identified as Streptomyces sp. based on the biochemical and atomic force microscope observation. The culture filtrate of Streptomyces sp. VSMGT1014 remarkably inhibited the mycelial growth and conidial and sclerotial germination of many fungal pathogens such as Macrophomina phaseolina, Fusarium oxysporum, Fusarium udum, and Alternaria alternata. The strain Streptomyces sp.VSMGT1014 produced five different compounds with Rf value ranges: 0.46, 0.51, 0.61, 0.85, and 0.89. Ethyl acetate extract of crude metabolite from VSMGT1014 significantly inhibited the mycelia growth of most of the fungal pathogens as well as sclerotial germination of R. solani.