Isolation and Characterization of a Marine Bacterium from Sundarbans, Bangladesh

Aims: Marine environment is a vast but represents a largely untapped source for isolation of new microorganism having ability to produce novel bioactive compound(s). The present study was designed with an aim to discover and identify marine bacterial strain producing antibacterial metabolites from marine soil samples of Sundarbans, Bangladesh.
Study Design: We used serial dilution technique for isolation of marine bacteria, streak plate technique for screeninig of priliminery antibacterial activity, cover slip culture method for morphological characterization and the 16S rDNA sequencing approach for phylogenetic characterization.
Place and Duration of Study: Pharmaceutical Microbiology Research Laboratory, Department of Pharmacy, University of Rajshahi, Rajshahi-6205, Bangladesh between August 2010 and July 2011.
Methodology: A total of 39 bacterial colonies were isolated from the marine soils collected from different locations of Sundarbans, a mangrove forest of Bangladesh. Among them ANAM-39 was selected on the basis of morphological, cultural, physiological, biochemical and taxonomic characterization, and it exhibited the highest antibacterial activity against a series of test organisms.
Results: The 16S rDNA sequence of the strain ANAM-39 showed close similarity with Smithella propionica(95.99%), Syntrophus aciditrophicus (93.63%) and Syntrophus gentianae (93.17%). However, the cultural, morphological, physiological and biochemical characteristics of the strain and S. propionica were completely different. So, the strain ANAM-39 may not be assigned within the genus Smithella.
Conclusion: To confirm the taxonomic position of the strain further studies are needed in respect to the DNA relatedness studies, DNA-DNA hybridization, small subunit (SSU) sequences, cell wall composition and other characterization.