Assessment of bioactivity of endophytic actinomycetes from some medicinal plants

Out of 70 isolates of actinomycetes obtained from medicinal plants, 21 displayed antagonistic activity against Alternaria alternata, Fusarium oxysporum and Rhizoctonia solani. All the isolates were screened for hydrolytic enzymes production. Among these, 47 isolates produced amylase, 25 protease and 16 were having ability to produce chitinase. The extracellular chitinase activity of two selected isolates AR3 and O9 was evaluated (0.083 and 0.080 U/ml) with 0.6% colloidal chitin, which was found better as compared to 1% colloidal chitin. Scanning electron microscopy revealed rupture of F. oxysporum mycelial cell wall at the area of interaction with O9. The endophytic actinomycete isolate O9 was identified as Streptomyces rochei strain KMB-1 by 16S rDNA sequencing. This isolate was found to be promising in terms of seed germination and Fusarium wilt control in muskmelon under green house conditions.