ISOLATION AND SCREENING OF NOVEL STREPTOMYCES FROM SEDIMENTS OF BAY OF BENGAL NEAR SRIKAKULAM COAST

Abstract

Objective: The Objective of this research is to isolate and screen potent antibiotic producing actinomycetes from unexplored regions of Bay of Bengal Near Srikakulam Coast.Methods: The isolation and screening were done on starch casein agar media. Antimicrobial activity screening was done using cross streak method and agar diffusion method. Further, Morphological characterization of the isolate was done using Scanning electron Microscopy (SEM-JSM 6610). Further, the cultural characterization of the isolates was done using standard protocols.Results: A total of sixty-eight isolates of Actinomycetes were collected from marine sediments of coastal line of Srikakulam district of Andhra Pradesh, which is one of the longest coastal lines of Andhra Pradesh. Due to its longest coastal line and geographical distribution, there are promising chance of diversity of the microorganisms and antibiotic producing potential. Each isolate was tested against various bacteria. Among all the isolates twelve isolates were promising and showed good antimicrobial activity. Within twelve isolates the isolate A-10 was very promising and showed antibiotic potential against most of the tested bacteria. This isolate appears to produce high anti-bacterial compounds on potato dextrose agar and nutrient agar medium respectively by using the agar diffusion method. The potent Actinomycete A-10 was further characterised by morphological methods consist of macroscopic and microscopic methods. The mycelium structure, colour and arrangement of conidiophores were observed through the oil immersion (100X). The strain was grown on Starch-Casein agar medium for morphological study using Scanning Electron microscopy. Scanning Electron micrographs of the strain A-10 results that the spore chain was straight and with more than 20 spores per chain. The spores are cylindrical in shape and had a smooth surface. Whirls, sclerotic granules, sporangia and flagellate spores were not observed. Further various biochemical tests performed for the identification of potent isolates are as follows: Melanin reaction, H2S production, tyrosine reaction, starch hydrolysis, casein hydrolysis, gelatin hydrolysis, milk coagulation and peptonization, nitrate reduction, temperature range of growth, pH tolerance and cell wall type by comparing all these results with the Bergey’s manual of Determinative Bacteriology and the organisms were identified. The isolate was identified as Streptomyces sp.Conclusion: Thus the result of antibacterial screening represents that the coastal area of Srikakulam is a potential source of antibiotic producing actinomycetes. Further the phylogenic tree construction and purification of the antibiotic principle from A-10 were under investigation.Keywords: Actinomycetes, Marine Sediments, Starch-Casein agar, SEM