Comparative Immunology, Microbiology & Infectious Diseases 30 (2007) 33–40 Genotyping of Edwardsiella tarda isolated from freshwater fish culture system Madushmita Acharya, N.K. Maiti , S. Mohanty, Pushpita Mishra, M. Samanta Microbiology Section, Central Institute of Freshwater Aquaculture, Kaushalyaganga Bhubaneswar 751002, Orissa, India Accepted 22 September 2006 Abstract The applicability of PCR-RFLP of 16S rDNA and conventional phenotypic methods for differentiation of Edwardsiella tarda associated in freshwater fish culture system was studied. In this study, by conventional biochemical tests and antibiotic resistant patterns 2 and 14 groups were obtained. But these methods failed to discriminate the isolates habitat wise. However, PCR-RFLP of 16S rDNA was found to be specific to detect habitat-specific isolates. All the fish isolates belonging to particular genotypes were found only in fish, not in water or sediment. Some of the genotypes were exclusively present in water and sediment. This study indicates the prevalence of site-specific genotypes in freshwater ecosystems. Molecular method is found to be superior to discriminate the E. tarda habitat wise to conventional typing methods. r 2006 Elsevier Ltd. All rights reserved. Keywords: Genotypying; Edwardsiella tarda; Freshwater; PCR; 16S rDNA; RFLP; Phenotyping Re´ sume´ L’applicabilite´ de PCR - RFLP de l’ADN de 16S r et des me´ thodes phe´ notypiques conventionnelles pour la diffe´ rentiation du tarda d’Edwardsiella associe´ e dans le syste` me d’eau ARTICLE IN PRESS www.elsevier.com/locate/cimid 0147-9571/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.cimid.2006.10.003 Corresponding author. E-mail address: maitink@yahoo.co.in (N.K. Maiti).