Isolation of antagonistic actinomycetes species from rhizosphere of non bt-cotton
T. sujatha, M. Ramadevi, P. Siva Raagini, K. Ushasri
The plant microbe interaction in the rhizosphere is one of the major factors regulating the health and growth of plants. Actinomycetes are common filamentous soil microorganisms important in maintaining a satisfactory biological balance in the soil, largely because of the ability to produce antibiotics. In the present study Antagonistic Actinomycetes species was isolated from rhizosphere of Non Bt cotton. Eight types of actinomycetes colonies were isolated from crowded plate method and were screened primarily by Giant colony technique. Three strains with best antifungal activity were further screened by Well Diffusion method and the best member which has good antifungal activity was selected and named as NBtAS. This strain was studied for itâ€™s morphological, physiological characteristics according to Bergeyâ€™s Manual and further studied by molecular characterization and was identified as Streptomyces violatus. The antagonistic nature of the isolated strain was determined for its anti-fungal activity by Well Diffusion method, MIC and Inhibition of phytopathogenic fungi like A. alternata, F. moniliformae, M. phaseolina, R. solaniand A. nigerin liquid medium. The results indicate that Streptomyces violatus isolated from rhizosphere of Bt cotton has Good Antifungal activity and it was more effective against Macrophomenaphaseolinawhen compared with other test fungi.