title: Decolorizing activity of malachite green and its mechanisms involved in dye biodegradation by Achromobacter xylosoxidans MG1.
abstract: An Achromobacter xylosoxidans MG1 strainisolated from the effluent treatment plant of a textile and dyeing factory from Yunnan Province in China was found capable of decolorizing the malachite green dye at a high efficacy. Strain MG1 reduced 86% malachite green at the concentration of 2,000 mg/l within 1 h, representing a greater ability for decolorizing and a higher tolerance of this compound than all previously reported bacteria. Color removal was optimal at pH 6 and 38°C. Further experimental evidences demonstrated that both cytoplasmic and extracellular biodegradation contributed to the decolorization of malachite green. Nested PCR was employed to identify the candidate genes responsible for malachite green decolorization, and we identified a cytoplasmic triphenylmethane reductase gene with 100% amino acid similarity to the corresponding gene in Citrobacter sp. strain. In contrast to our expectation, the addition of metyrapone had little effect on the cytoplasmic biodegradation, suggesting that cytochrome P450 was not involved in the high-performance reduction. The extracellular biodegradation was likely attributable to the secretion of extracellular proteases and some heat-resistant compounds.
authors.affiliation: Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China.
authors.forename: Ji'ai
authors.initials: J
authors.lastname: Wang
authors.forename: Min
authors.initials: M
authors.lastname: Qiao
authors.forename: Kangbi
authors.initials: K
authors.lastname: Wei
authors.forename: Junmei
authors.initials: J
authors.lastname: Ding
authors.forename: Zhongzhong
authors.initials: Z
authors.lastname: Liu
authors.forename: Ke-Qin
authors.initials: KQ
authors.lastname: Zhang
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Huang
mesh_terms: D042441:Achromobacter denitrificans / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001673:Biodegradation, Environmental; D002681:China; D003116:Color; D004396:Coloring Agents / Q000378:metabolism*; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D012394:Rosaniline Dyes / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013783:Textile Industry; D014320:Triphenylmethyl Compounds / Q000378:metabolism*; D014865:Waste Disposal, Fluid
chemical_list: D001426:Bacterial Proteins; D004396:Coloring Agents; D012394:Rosaniline Dyes; D014320:Triphenylmethyl Compounds; C005095:malachite green; C046945:triphenylmethane; D010088:Oxidoreductases