Functional and Molecular Characterization of Native Isolates of Actinomycetes From Soil and Endorhizosphere of Medicinal Plants
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Date
2011
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UAS, Dharwad
Abstract
Microbial metabolic repertoire represents the primary resources from which
new biomolecules are derived. Recently, the rise of resistance in pathogens renewed
the interest on actinobacteria. In the present study, a total of 248 actinomycetes
colonies were recovered from rhizosphere, endorhizosphere of 27 medicinal plants, an
aquatic weed and road side run off soil. Randomly 114 actinobacteria isolates were
picked for functional characterization against Rhizoctonia solani, Sclerotium rolfsii,
Colletotrichum capsici, Ralstonia solanacearum and 40 actinobacteria against an
insect Plutella xylostella. Out of which, 25, 85.5, 16 and 10 per cent of total isolates
displayed an antagonism of (90-100) per cent against Rhizoctonia solani, Sclerotium
rolfsii, Colletotrichum capsici, Ralstonia solanacearum respectively, and 20 isolates
displayed more than 50 per cent mortality against Plutella xylostella. 26 isolates were
selected for identification due to its functional significance through ARDRA. They
were found to be members of Streptomyces, Microbispora, Nonomuraea and
Amycolatopsis genera. Similarly, 16S rDNA sequence analysis of 11 extra potent
isolates out of 26 isolates clustered them into Streptomyces genera. The REP PCR
fingerprinting of whole genome of all these 26 isolates displayed 75 per cent identity
among themselves. Supplementing to functional capability of these isolates 76 and 52
per cent total isolates were positive for NRPS and PKS I genes respectively. Cloning
of partial sequence of PKS I gene of AUDT 248 exhibited an identity to the
antibiotics, stambomycin gene cluster which was further supplemented with LC-MS
analysis. Similarly, partial PKS I gene of AUDT 217 showed homology to the
modular PKS of unknown biosynthetic identity.
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Plant Biotechnology