B Madhusudana Rao1, P K Surendran. 1. Microbiology, Fermentation & Biotechnology Division, Central Institute of Fisheries Technology, Cochin, India.
Abstract
AIMS: The genetic diversity of Vibrio cholerae isolated from black tiger shrimp (Penaeus monodon) aquaculture farms was determined using three PCR typing methods based on enterobacterial repetitive intergenic consensus (ERIC) sequences, ribosomal gene spacer (RS) sequence and repetitive extragenic palindromic (REP) sequences. METHODS AND RESULTS: Non-O1 and non-O139 V. cholerae isolates were obtained from shrimp pond water, pond sediment, shrimp head and shrimp muscle. RS-PCR yielded fewer bands than REP-PCR and ERIC-PCR. Higher similarity was observed in RS-PCR (75-100%) than in REP-PCR (60-95%) and ERIC-PCR (40-95%). CONCLUSIONS: A 100% similarity between V. cholerae isolates was only noticed in RS-PCR. The choleratoxigenic V. cholerae (non-O1 and non-O139) showed greater genetic similarity with ctx-negative V. cholerae than among ctx-positive V. cholerae. SIGNIFICANCE AND IMPACT OF THE STUDY: The greater similarity of ctx-positive V. cholerae with ctx-negative V. cholerae isolates indicates that the ctx-positive strains (non-O1 and non-O139) might have originated from autochthonous V. cholerae in the aquatic niche.
AIMS: The genetic diversity of Vibrio cholerae isolated from black tiger shrimp (Penaeus monodon) aquaculture farms was determined using three PCR typing methods based on enterobacterial repetitive intergenic consensus (ERIC) sequences, ribosomal gene spacer (RS) sequence and repetitive extragenic palindromic (REP) sequences. METHODS AND RESULTS:Non-O1 and non-O139 V. cholerae isolates were obtained from shrimp pond water, pond sediment, shrimp head and shrimp muscle. RS-PCR yielded fewer bands than REP-PCR and ERIC-PCR. Higher similarity was observed in RS-PCR (75-100%) than in REP-PCR (60-95%) and ERIC-PCR (40-95%). CONCLUSIONS: A 100% similarity between V. cholerae isolates was only noticed in RS-PCR. The choleratoxigenic V. cholerae (non-O1 and non-O139) showed greater genetic similarity with ctx-negative V. cholerae than among ctx-positive V. cholerae. SIGNIFICANCE AND IMPACT OF THE STUDY: The greater similarity of ctx-positive V. cholerae with ctx-negative V. cholerae isolates indicates that the ctx-positive strains (non-O1 and non-O139) might have originated from autochthonous V. cholerae in the aquatic niche.