Isolation and Characterization of Bioactive Compounds from Marine Microbes
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Date
2016-09
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University of Agricultural Science, Dharwad
Abstract
The present investigation was carried out to exploit the anti-phytopathogenic property of marine microbes. Several microbial cultures (four hundred thirty) isolated from the marine water and sediment samples from coastal parts are maintained at Department of Biotechnology, UAS, Dharwad. Among these resources sixty one bacterial, fifty fungal and forty one actinomycetes viable isolates were selected for investigation. These isolates were tested for anti-phytopathogenic activity against Sclerotium rolfsii, Fusarium oxysporum, Colletotrichum sp. and Ralstonia solanacearum in vitro. Three isolates (AUDI-172 from bacteria, AUDI-585 from fungi and AUDI-841 from actinomycete) showed good anti-phytopathogenic activity against all phytopathogens. The molecular characterization of potent microbial isolates were done based on 16s rDNA region for bacteria and actinomycete whereas internal transcribed spacer (ITS) region for fungi. BLAST analysis showed bacterial isolate as Enterobacter cloacae, actinomycete as Streptomyces macrospores and potent fungus as Debaryomyces hansenii.
To find out bioactive compounds, secondary metabolites from these potent isolates were extracted using ethyl acetate solvent-solvent extraction method and again tested for antimicrobial activity against the phytopathogens. Functional groups of bioactive compounds were characterized by using gas chromatography-mass spectrometry (GCMS) from the crude extract of potent isolates. Twelve different bioactive compounds were identified from the potent isolates of bacteria and fungi. Thirteen bioactive compounds were identified from potent actinomycete. Mostly, secondary metabolites are the products of polyketide synthesis (PKSs) and non-ribosomal peptide synthesis (NRPSs) gene clusters. Degenerative primer pairs were used for the amplification of gene fragments from PKS-1 and NRPS gene clusters. Presence of PKS-1 and NRPS gene fragments were confirmed in the potent isolates. The present study depicts a promising scenario to focus on marine microbial derived bioactive compounds against phytopathogens. In vivo analysis of these bioactive compounds can help to identify novel biocontrol agents against phytopathogens.