ISOLATION, IDENTIFICATION AND ANTIMICROBIAL POTENTIAL OF MARINE Streptomyces spp FROM COASTAL REGIONS OF ANDHRA PRADESH, INDIA

Author(s): Mary Swapna Mogili and Vijayalakshmi Muvva*

Abstract: Studies on bioactive actinobacteria from saline soil are very scanty and in the present study an initiative has been taken to isolate culturable halophilic actinobacteria and to screen their bioactive potential. The marine sediment samples were collected from the coastal regions of Andhra Pradesh, India and isolations were carried out by using Yeast extract malt extract dextrose (YMD) agar medium. Identification of the strains was carried out by polyphasic taxonomical studies including morphological, cultural, physiological, biochemical characters along with16S rRNA analysis. The isolates were subjected to fermentation and the crude extract was screened for antimicrobial activity by agar diffusion assay. The 16S rRNA sequence of the isolates showed 100% similarity with Streptomyces vinaceusdrappus and Streptomyces rectiverticillatus. The growth was maximal in the designed production medium with the incubation temperature of 37ºC and pH of 7.0 with 3% NaCl. The crude extracts of these isolates also exhibited significant antagonistic activity against fungi (Aspergillus flavus, Candida albicans and Penicillium citrinum) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris and Xanthomonas campestris) as well as Gram positive bacteria (Staphylococcus aureus, Bacillus megaterium and Bacillus subtilis). The actinobacterial strains isolated from marine sediments were identified as Streptomyces vinaceusdrappus VJMS-4 and Streptomyces rectiverticillatus VJMS-8 which were moderately halophilic and produced extracellular bioactive metabolites, active against fungal and bacterial pathogens. Further studies on purification and characterization of the bioactive compounds from the strains are in progress. The results of this study suggested that the marine actinobacteria from the unexplored Indian coast could provide lead compounds of therapeutic value.

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