Bangladesh Journal of Pharmacology Volume: 11; Number 1; Year 2016 Cite this article as: Gopikrishnan V, Radhakrishnan M, Pazhanimurugan R, Shanmugasundaram T, Balagurunathan R. In vitro antimicrobial activity of actinobacteria from South East Coast of Tamil Nadu, India. Bangladesh J Phar- macol. 2016; 11: 190-91. In vitro antimicrobial activity of actinobacteria from South East Coast of Tamil Nadu, India Sir, The emerging multidrug resistance pathogenic micro- bes are emphasizing the need of newer antimicrobials (Baltz, 2007). Actinobacteria are the most economically valuable prokaryotes which are well known to produce chemically diverse metabolites with wide range of biological activities (Balagurunathan et al., 2010). Now a days, bioprospecting of marine derived actinobac- teria, when compared to those from terrestrial sources, results in the isolation of novel antimicrobials. With this view, we attempted to study the in vitro antimicrobial activity of actinobacteria from South East coast of India. Bioactive compounds from 50 actinobacterial strains isolated from Pitchavaram (P) and Parangipettai man- grove (PM) and estuarine (PE) sediments, Southeast coast of Tamil Nadu, were produced by agar surface fermentation using yeast extract malt extract agar. After 10 days of incubation all the actinobacterial cultures were screened for antimicrobial activity against Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae by agar plug method (Radhakrishnan et al., 2014). Crude bioactive compounds from two potential strains PE7 and PM 33 were produced by submerged and agar surface fermentation and tested for every 24 hours against S. aureus till 12th day of fermentation (Gopi- krishnan et al., 2013). Among 50 actinobacterial strains, actinobacteria from Parangipettai mangrove and estuarine ecosystems were showed promising activity when compared to actino- bacteria isolated from Pitchavaram ecosystem (Figure 1). About 40 strains were active only against Gram- A Journal of the Bangladesh Pharmacological Society (BDPS) Bangladesh J Pharmacol 2016; 11: 190-191 Journal homepage: www.banglajol.info Abstracted/indexed in Academic Search Complete, Agroforestry Abstracts, Asia Journals Online, Bangladesh Journals Online, Biological Abstracts, BIOSIS Previews, CAB Abstracts, Current Abstracts, Directory of Open Access Journals, EMBASE/Excerpta Medica, Google Scholar, HINARI (WHO), International Pharmaceutical Abstracts, Open J-gate, Science Citation Index Expanded, SCOPUS and Social Sciences Citation Index ISSN: 1991-0088; DOI: 10.3329/bjp.v11i1.26329 Letter to the Editor Figure 1. Number of antagonistic actinobacteria isolated from different marine ecosytems http://www.bioxbio.com/if/html/BANGL-J-PHARMACOL.html positive bacteria, 18 strains were active only against Gram-negative bacteria whereas 18 strains showed broad spectrum activity against both Gram-positive and Gram-negative bacteria. Two actinobacterial strains such as PM33 and PE7 from Parangipettai mangrove rhizosphere and estuarine ecosystem, respectively, were showed broad spectrum activity against all the clinical pathogens tested. When compared with liquid fermentation, solid state fermentation showed good growth and promising activity till end of 12th day. In the present study, both the potential actinobacterial strains produced the bioactive metabolites very earlier in the YEME agar (Table I). Further production and isolation of active principles from the actinobacterial strains PM33 and PE7 will be worth pursuing. V. Gopikrishnan1, M. Radhakrishnan1, R. Pazhanimurugan2, T. Shanmugasundaram2 and R. Balagurunathan2 1Centre for Drug Discovery and Development, Sathyabama University, Chennai 119. Tamil Nadu, India; 2Department of Microbiology, Periyar University, Salem 11, Tamil Nadu, India. Corresponding author: email: rbalaguru@yahoo.com References Baltz R. Antimicrobials from actinomycetes: Back to future. Microbe 2007; 2: 125-31. Radhakrishnan M, Gopikrishnan V, Balaji S, Balagurunathan R, Vanaja Kumar. Bioprospecting of actinomycetes from cer- tain less explored ecosystems active against Mycobacterium tuberculosis and other non-mycobacterial pathogens. Int Sch Res Notices. 2014, 2014. Balagurunathan R, Radhakrishnan M. Biotechnological, gene- tic engineering and nanotechnological potential of actino- mycetes. In: Industrial exploitation of microorganisms. Maheshwari DK, Dubey RC, Saravanamuthu R. (eds). New Delhi, International Publishing House Pvt Ltd, 2010, pp 302- 21. Gopikrishnan V, Pazhanimurugan R, Shanmugasundaram T, Radhakrishnan M, Balagurunathan R. Bioprospecting of actinobacteria from mangrove and estuarine sediments for antifouling compounds. Int J Innov Sci Eng Technol. 2013; 2: 2726-35. 191 Bangladesh J Pharmacol 2016; 11: 190-191 Table I Antagonistic activity of potential actinobacterial strains PM 33 and PE7 Clinical pathogens (Zone of inhibition in mm) Actinobacterial strains S. aureus B. subtilis E. coli P. aeruginosa K. pneumoniae Strain PM33 15 ± 0.58 16 ± 0.58 14 ± 0.00 16 ± 0.58 14 ± 0.00 Strain PE7 15 ± 0.58 17 ± 0.00 12 ± 0.58 16 ± 0.58 13 ± 0.58 mailto:rbalaguru@yahoo.com DatePrinted: This article was downloaded by you on: Jan 18, 2016