title: Kinetics of arsenite oxidation by Variovorax sp. MM-1 isolated from a soil and identification of arsenite oxidase gene.
abstract: A Gram-negative, arsenite-oxidizing bacterial strain, MM-1 tolerant to 20mM arsenite and 200 mM arsenate was isolated from a heavy metal contaminated soil which contained only 8.8 mg kg(-1) of arsenic. Based on 16S rRNA analysis, the strain was closely related to the genus Variovorax. This strain completely oxidized 500 μM of arsenite to arsenate within 3h of incubation in minimal salts medium. Kinetic studies of arsenite oxidation by the cells showed one of the lowest Km (17 μM) and highest Vmax (1.23 × 10(-7) μM min(-1) cell(-1)) values reported to date for whole cell suspension. PCR analysis using degenerate primers confirmed the presence of arsenite oxidase gene and its amino acid sequence was 70-91% identical to the large subunit of most reported arsenite oxidases. The significant arsenite oxidation capacity shown by the strain opens the way to its potential application in arsenic remediation process.
authors.affiliation: Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, Mawson Lakes Boulevard, Mawson Lakes, SA 5095, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Mawson Lakes Bvd., Mawson lakes, SA 5095, Australia.
authors.forename: Md Mezbaul
authors.initials: MM
authors.lastname: Bahar
authors.forename: Mallavarapu
authors.initials: M
authors.lastname: Megharaj
authors.forename: Ravi
authors.initials: R
authors.lastname: Naidu
mesh_terms: D001151:Arsenic / Q000737:chemistry; D018053:Arsenites / Q000737:chemistry; D020562:Betaproteobacteria / Q000201:enzymology* / Q000235:genetics*; D001673:Biodegradation, Environmental; D003001:Cloning, Molecular; D017931:DNA Primers; D005798:Genes, Bacterial; D007700:Kinetics; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics*; D010100:Oxygen / Q000737:chemistry; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012987:Soil; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis
chemical_list: D018053:Arsenites; D017931:DNA Primers; D012336:RNA, Ribosomal, 16S; D012987:Soil; D012989:Soil Pollutants; D010088:Oxidoreductases; C078179:arsenite oxidase; C015001:arsenite; D001151:Arsenic; D010100:Oxygen
keywords: Arsenic tolerance; Arsenite oxidase gene; Arsenite oxidation; Arsenite oxidizing bacteria; Detoxification