First Report of Antimicrobial Spectra of Novel Strain of Streptomyces tritolerans (Strain AS1) Isolated from Earthworm Gut (Eisenia foetida) Against Plant Pathogenic Bacteria and Fungi

This is the first report on antagonistic activity of a new strain of Streptomyces tritolerans (strain AS1) isolated from earthworm gut (Eisenia foetida) against plant pathogenic bacteria and fungi. Actinomycetes particularly Streptomyces sp. enhance soil fertility and have antagonistic activity against wide range of soil borne plant pathogens which had received special attention. The main objective of the study was to isolate and screen for antagonistic activity exhibiting actinomycetes from an earthworm gut. In search for metabolites of Actinomycetes having antibacterial and antifungal activity against cosmopolitan plant pathogens 20 isolates were screened. Among all, strain AS1 that was identified as a new strain of S. tritolerans, showed high level of activity in dual culture bioassay and well diffusion methods. AS1 was discovered to be a novel strain of Streptomyces tritolerans sp. and the 16S rRNA gene sequence was deposited at GenBank with accession no EU623448. Ethyl acetate extract obtained from AS1 strain was tested for its antagonistic potentiality against test organisms (phytopathogenic bacteria and fungi) and showed good inhibition levels (20-40 mm). Due to its Antimicrobial potentiality on wide range of plant pathogens, Streptomyces tritolerans (strain AS1) would play an important role in integrated biocontrol programmes.