CiiT International Journal of Biometrics and Bioinformatics, Vol 3, No 9, September 2011 434 0974-9675/NT-BEECOM-041/05/$20/$100 © 2011 CiiT Published by the Coimbatore Institute of Information Technology Abstract---The bacteria isolated from the surface of the corals were found to have an inhibitory effect against 10 human pathogens. It was observed that out of 318 and 345 bacterial strains isolated from the surface of Favites abdita and Turbinaria mesenterina respectively, 12% was found be potent producers with maximum inhibition against Staphyloccus aureus (6 mm) and Streptococcus pneumonia (6 mm). It was observed in that the same percentage (12%) of bacterial strains isolated from Turbinaria mesenterina. Gram-positive, Gram-negative, pigmented and non-pigmented strains were all found to be antibiotic producers without exceptions. However, the antibiotic producing strains consisted of a higher percentage of non-pigmented strains in comparison with that of the pigmented ones, Favites abdita (38/288 strains), Turninaria mesenterina (41/304 strains). These results suggest that the epiphytic bacteria isolated from these corals could be effectively used for the development of novel drugs to combat the pathogens producing diseases to humans. Keywords---Corals, Marine Bacteria, Antagonistic Activity, Human Pathogens I. INTRODUCTION ICROORGANISMS are a rich source of new metabolites with a wide variety of biological activities, and some of them display significant practical applications. Marine microorganisms are of considerable current interest as a new and promising source of biologically active compounds. They produce a variety of metabolites, some of which can be used for drug development. Recently it was found that some bioactive compounds isolated from invertebrates originate from symbiotic microorganisms. In the past two decades, the pharmaceutical industry has been successful in containing problems due to single resistance determinants. However, the advent of multiple resistance mechanisms has severely limited the effective use of many major classes of drugs. So searches for new drug classes with novel mechanism of action are of relevance. There is a growing concern about the use and particularly the abuse of antimicrobial drugs not only in human medicine but also in aquaculture. Hence, the need of the hour is a search for novel antibacterial compounds with Manuscript received on August 16, 2011, review completed on August 31, 2011 and revised on September 14, 2011. Dr. C. Chellaram is with the Department of Biomedical Engineering, Vel Tech Multi Tech Dr. Rangarajan Dr. Sakunthala Engineering College, Chennai. Tamilnadu. India. Phone: +91-9944040538; Fax: 044-26841061; E-Mail: chellarampublications@gmail.com Dr. T. Prem Anand is with the Department of Biomedical Engineering, Vel Tech Multi Tech Dr. Rangarajan Dr. Sakunthala Engineering College, Chennai. Tamilnadu. India. Digital Object Identifier No. BB092011008 therapeutic potential for which the pathogens may not have developed resistance (Patil et al., 2001). Interactions between epibiotic marine bacteria and their host organisms are known to play a significant role in marine ecosystems but this association has received little attention. The important microhabitats for marine bacteria are the sediments, biotia and abiotic and internal tissues of invertebrates. Marine plants and animals are well known to have developed symbiotic relationships with numerous microbes. The study of marine bacteria has also led to the realization that microorganism form specific symbiotic relationship with marine organisms which may be responsible for the production of some bioactive compounds There is a profuse literature to cite the association of bacteria with marine organisms including, seaweeds (Lemos et al., 1985), corals (Chellaram and Patterson, 2009 and Dobretsov and Qian, 2004), molluscs (Chellaram et al, 2004) and sponges (Chelossi et al., 2004). Marine macro organisms are well known to have developed symbiotic relationships with numerous microorganisms. This is particularly true of the bacteria, which are widely distributed on the surfaces and within the tissues of marine animals. The importance of bacterial symbiosis is growing in recognition that bacteria may be the true producers of many compounds isolated from marine organisms (Fenical, 1993). So the present work is also aimed to isolate the surface bacteria from the selected two corals, Favites abdita and Trurbinaria mesenterina and to test the inhibitory effect of the isolates against selected 10 human pathogens. II. MATERIALS AND METHOD Viable heterotrophic bacteria were obtained by swabbing a small area (1 cm 2 in triplicates) of the external surface of live hard corals, Favites abdita and Turbinaria mesenterina from Tuticorin coastal waters, South east coast of India, using a sterile cotton swab, which was then placed in 2ml of sterile seawater and vortexed. Serial 10-fold dilutions of each solution were prepared and aliquots (0.1ml) were plated on Zobell Marine Agar 2216 (ZMA) (Chelossi, et al, 2004). Plates were incubated for 7 days at 27ºC. Perceptible different morphotypes were isolated in pure culture on ZMA. Bacterial isolates were kept in ZMA slants at 4ºC. The number of pigmented and non-pigmented strains was noted. Gram staining was performed for all the isolated strains. To test the antagonistic effect of the isolated bacterial strains, 10 human pathogens [Escherichia coli (ATCC 25922), Shigella dysentriae (ATCC 13313), Staphylococcus epidermidis Antagonistic Effects of Coral Reef Associated Bacteria from South Eastern India C. Chellaram and T. Prem Anand M