Abstract
The most common bacterial mercury resistance mechanism is based on the reduction of Hg 2+ to Hg 0 , which is dependent on the mercuric reductase enzyme (merA) activity. The aims of this research were to isolate and characterize merA gene fragment of mercury resistant bacteria Klebsiella pneumoniae isolate A1.1.1. The gene fragment was amplified by PCR using previously designed primer pairs. Plasmid DNAs were used as template. The result showed that the partial sequence of merA gene has been found on plasmid DNA of mercury resistant bacterium Klebsiella pneumoniae isolates A1.1.1. The nucleotide sequence of the merA gene consists of 285 base pairs (bp) which encodes deduced 94 amino acids of mercury reductase merA protein. The merA protein sequence of isolate A1.1.1 has 99% similarity with some strains of Klebsiella pneumoniae deposited in Gen Bank. There is a gene mutation that causes the deduced amino acid threonine was replaced by serine at position 524 (Thr→Ser) in the merA protein of Klebsiella pneumonia as the accession number: AAR91471.1.
Highlights
Mercury is a toxic compound that is widely distributed in the global environment and can accumulate in the food chain (Jan et al, 2009)
Ni Chadhain et al (2006), which uses the same primer obtained mercuric reductase enzyme (merA) gene in genomic DNA of bacterial isolated from marine sediment
To study the similarity of nucleotides sequence from merA gene of Klebsiella pneumoniae isolate A1.1.1 with merA gene of Klebsiella pneumoniae deposited in GenBank, blast analyzes was conducted by online at http://blast.ncbi.nlm.nih.gov/Blast.cgi.Blast result shows that merA gene of isolate A1.1.1 has 93% similarities with merA gene of Klebsiella pneumoniae deposited in GenBank
Summary
Mercury is a toxic compound that is widely distributed in the global environment and can accumulate in the food chain (Jan et al, 2009). Mercury pollution continuously increases from time to time as a result of human activities such as the growth of electronics industry, the increasing use of antimicrobial agents, vaccines, amalgam, cosmetics and the higher activity of gold mines using mercury to extract gold (Jan et al, 2009; Schelert et al, 2004). Various conventional techniques have been used to dispose toxic metals including preparation and chemical separation, oxidation-reduction reactions, ion exchange, reverse osmosis, filtration, adsorption using activated carbon, electrochemical and evaporation. Those techniques were considered ineffective, especially for metal concentrations less than 100 mg/L and quite expensive and their supporting chemicals become secondary pollutants (Habashi, 1978). Staphylococcus, Bacillus, Pseudomonas, Citrobacteria, Klebsiella and Rhodococcus are often used in microbial bioremediation for mercury (Adeniji, 2004)
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