Optimization of Culture Conditions for Enhanced Antimicrobial Activity of Rhodococcus erythropolis VLK-12 Isolated from South Coast of Andhra Pradesh, India.

Aims: To Isolate and characterize the antimicrobial actinomycetes from the marine habitats of south coast of Andhra Pradesh, India. Place and Duration of the Study: Marine habitats of south coast of Andhra Pradesh, India, between June 2011 and July 2012. Methodology: The soil samples were collected, pre-treated and plated on yeast extractmalt extract dextrose agar medium. Identification of the strain was carried out by employing the polyphasic taxonomical studies including the 16S rRNA sequence based analysis. Phylogenetic tree was constructed using the Molecular Evolutionary Genetic Analysis (MEGA) version 5. The influence of culture conditions and the effect of environmental factors on the biomass and antimicrobial activy\ity of the strain was the focus of this study. Results: A total of 20 actinobacteria were isolated from the marine habitats of south coast of Andhra Pradesh, India, and screened for antimicrobial activity against test bacteria and fungi. The potent bioactive metabolite producing strain was designated as VLK-12. Further polyphasic studies revealed that the Isolate VLK-12 belongs to the genera Rhodococcus. Phylogenetic analysis of 16S rRNA sequencing studies revealed that the strain is closely related to Rhodococcus erythropolis. The crude ethyl acetate extract obtained by culturing the strain on YMD inhibited Gram positive and Gram negative bacteria along with fungi. Conclusion: Rhodococcus erythropolis isolated from the marine habitats of south coast of Andhra Pradesh exhibited antimicrobial activity against pathogens.