Remediation of Chromium(VI) by a Methane-Oxidizing Bacterium

• Published in: Environmental science & technology Vol. 44; no. 1; pp. 400 - 405
• Main Authors: Al Hasin, Abubakr, Gurman, Stephen J, Murphy, Loretta M, Perry, Ashlee, Smith, Thomas J, Gardiner, Philip H. E
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.01.2010
• Subjects: Applied sciences; Bacteria; Bioremediation; Chromium; Chromium - metabolism; Environmental Restoration and Remediation; Exact sciences and technology; Genomics; Greenhouse gases; Methane; Methane - metabolism; Methylococcus - metabolism; Methylococcus capsulatus; Microorganisms; Microscopy, Electron, Transmission; Oxidation; Oxidation-Reduction; Pollution; Remediation and Control Technologies; Spectrum analysis; Spectrum Analysis - methods; Methane; Phosphates; Growth; X ray spectrometry; Modeling; Heavy metal; Trace element; Decontamination; Greenhouse gas; Chromium; Bacteria; Air pollution; Poison; Phosphorus compound; Models; Oxidation; Bioremediation; Microorganism
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es901723c

Methane-oxidizing bacteria are ubiquitous in the environment and are globally important in oxidizing the potent greenhouse gas methane. It is also well recognized that they have wide potential for bioremediation of organic and chlorinated organic pollutants, thanks to the wide substrate ranges of the methane monooxygenase enzymes that they produce. Here we have demonstrated that the well characterized model methanotroph Methylococcus capsulatus (Bath) is able to bioremediate chromium(VI) pollution over a wide range of concentrations (1.4−1000 mg L−1 of Cr6+), thus extending the bioremediation potential of this major group of microorganisms to include an important heavy-metal pollutant. The chromium(VI) reduction reaction was dependent on the availability of reducing equivalents from the growth substrate methane and was partially inhibited by the metabolic poison sodium azide. X-ray spectroscopy showed that the cell-associated chromium was predominantly in the +3 oxidation state and associated with cell- or medium-derived moieties that were most likely phosphate groups. The genome sequence of Mc. capsulatus (Bath) suggests at least five candidate genes for the chromium(VI) reductase activity in this organism.