Praveen, Kumar and Sabu , Thomas (2009) Presence of dfr6 Gene Cassette in Superintegron of Non-O1/Non-O139 Strain of Vibrio cholerae. ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, 53 (11). pp. 4959-4960. ISSN 0066-4804

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Abstract

Integrons, the DNA elements capable of capturing small mobile elements or gene cassettes, play a major role in the spread of antibiotic resistance in gram-negative bacteria. They are generally divided into two major groups: the multiresistance integrons (MRI), which carry mobile genetic elements, and the chromosomal superintegrons (SI). Gene cassettes carried by MRI encode resistance against antibiotics and are located in either chromosomes or plasmids. Based on the divergence of integrase genes, five classes of MRI have been reported (6). The SI identified in the genomes of the pathogenic Vibrio species sequenced to date have been found to contain a large number of gene cassettes, ranging from 72 to more than 200 (3, 7). The cassettes of the Vibrio cholerae SI were demonstrated to be substrates for the class 1 integrons of MRI (5, 8). Two class 1 integron gene cassettes, CARB4 and dfr6, were found to contain attC sites similar to those of V. cholerae repeats (VCRs) (5). Hence, it was predicted that such genes were recruited from SI. The strain identified (V. cholerae non-O1/non-O139, A444) was isolated from Vembanad Lake in the Allapuzha district of Kerala, India. The antimicrobial susceptibility test was done by using commercially available discs (Himedia). The presence of the SXT element and class 1 integrons was tested by PCR as described previously (1, 9). Shotgun cloning was performed by digesting genomic DNA with BfuC1 (NEB) and ligating the fragments with the BamHI (NEB)-digested pUC19 vector. The chemically competent Escherichia coli JM109 cells were transformed with a ligation mixture. The transformants were selected at 37°C on LB agar with ampicillin (100 mg/liter) and trimethoprim (TMP) (50 mg/liter). The plasmids from TMP-resistant clones were isolated and sequenced using a pUC/M13 universal pair of primers specific for the pUC series of vector. The sequencing was performed with an ABI Prism BigDye terminator kit using an ABI Prism 3100 DNA sequencer (Applied Biosystems). The nucleotide and deduced protein sequences were analyzed with BioEdit software (version 7.0.9.0; T. Hall, http://www.mbio.ncsu.edu/BioEdit/bioedit.html) and the BLAST search engine.

Item Type:	Article
Subjects:	Cholera And Biofilm
Depositing User:	Central Library RGCB
Date Deposited:	24 Sep 2019 05:54
Last Modified:	24 Sep 2019 06:15
URI:	http://rgcb.sciencecentral.in/id/eprint/873

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