title: Heavy Metal Resistances and Chromium Removal of a Novel Cr(VI)-Reducing Pseudomonad Strain Isolated from Circulating Cooling Water of Iron and Steel Plant.
abstract: Three bacterial isolates, GT2, GT3, and GT7, were isolated from the sludge and water of a circulating cooling system of iron and steel plant by screening on Cr(VI)-containing plates. Three isolates were characterized as the members of the genus Pseudomonas on the basis of phenotypic characteristics and 16S rRNA sequence analysis. All isolates were capable of resisting multiple antibiotics and heavy metals. GT7 was most resistant to Cr(VI), with a minimum inhibitory concentration (MIC) of 6.5 mmol L-1. GT7 displayed varied rates of Cr(VI) reduction in M2 broth, which was dependent on pH, initial Cr(VI) concentration, and inoculating dose. Total chromium analysis revealed that GT7 could remove a part of chromium from the media, and the maximum rate of chromium removal was up to 40.8 %. The Cr(VI) reductase activity of GT7 was mainly associated with the soluble fraction of cell-free extracts and reached optimum at pH 6.0∼8.0. The reductase activity was apparently enhanced by external electron donors and Cu(II), whereas it was seriously inhibited by Hg(II), Cd(II), and Zn(II). The reductase showed a Kmof 74 μmol L-1of Cr(VI) and a Vmaxof 0.86 μmol of Cr(VI) min-1mg-1of protein. The results suggested that GT7 could be a promising candidate for in situ bioremediation of Cr(VI).
authors.affiliation: Department of Biological Science and Biotechnology, School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, 122 Luoshi Road, Wuhan, 430070, People's Republic of China. jiankunzhang2005@163.com.
authors.forename: Jian-Kun
authors.initials: JK
authors.lastname: Zhang
authors.affiliation: Technological Center of Inspection and Quarantine, Hubei Entry-Exit Inspection and Quarantine Bureau, 588 Qintai Road, Wuhan, 430050, People's Republic of China.
authors.forename: Zhen-Hua
authors.initials: ZH
authors.lastname: Wang
authors.affiliation: Technological Center of Inspection and Quarantine, Hubei Entry-Exit Inspection and Quarantine Bureau, 588 Qintai Road, Wuhan, 430050, People's Republic of China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Ye
mesh_terms: D001673:Biodegradation, Environmental / Q000187:drug effects; D002857:Chromium / Q000302:isolation & purification* / Q000633:toxicity; D004352:Drug Resistance, Microbial / Q000187:drug effects; D004583:Electrons; D006863:Hydrogen-Ion Concentration; D007221:Industry; D007477:Ions; D007501:Iron; D007700:Kinetics; D008826:Microbial Sensitivity Tests; D010088:Oxidoreductases / Q000378:metabolism; D010641:Phenotype; D010802:Phylogeny; D011549:Pseudomonas / Q000302:isolation & purification* / Q000378:metabolism*; D012722:Sewage / Q000382:microbiology; D012995:Solubility; D013232:Steel; D014865:Waste Disposal, Fluid
chemical_list: D007477:Ions; D012722:Sewage; D002857:Chromium; D013232:Steel; C074702:chromium hexavalent ion; D007501:Iron; D010088:Oxidoreductases; C075965:chromium(VI) reductase
keywords: Bioremediation; Chromate reductase; Chromate reduction; Chromium removal; Heavy metal resistance; Pseudomonas sp.