Volume No. 9 Issue No.: 3A Page No.: 803-812 January-March 2015

 

HORIZONTAL GENE TRANSFER OF ARS GENES : A POS -SIBLE SOURCE OF ARSENIC DISSEMINATION IN SUBSURFACE ENVIRONMENT

 

Sarkar Angana and Sar Pinaki*

Department of Biotechnology, Indian Institute of Technology, Kharagpur, WB (INDIA)

 

Received on : September 14, 2014

 

ABSTRACT

 

Microbial arsenic (As) redox transformation has a key impact on As hydro-geochemistry which eventually influence the toxicity and mobility of this metalloid in subsurface environment. In this study forty-two arsenate (As5+) reducing bacteria were isolated and identified from As contaminated groundwater of West Bengal, India. Nearly 350 bp fragment of the gene encoding cytosolic arsenate reductase enzyme (ArsC) was sequenced for 30 morphotypes among the As5+ reducing bacteria. Gene encoding arsenite efflux pump protein (ArsB) was amplified and sequenced within 33% of the isolates. The sequence analysis suggested that all the arsC sequences clustered on the same clade with previously reported arsC genes of ?-proteobacterial members e.g. Escherichia coli, Vibrio sp., Pseudomonas sp. and Shigella sp., while their 16S rDNA sequences showed lineage to mostly ?-proteobacterial members. In case of arsB gene similar phylogenetic incongruence was also observed. The GC content analysis further supported the same indicating occurrence of Horizontal Gene Transfer (HGT) of the ars genes (particularly arsC, arsB) between the bacterial members within the contaminated aquifer

 

Keywords : Bacteria, HGT, As5+ reduction, ArsC, ArsB, Mobilization

 

 

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