Environmental biology

Identification and characterization of the chromium(VI) responding proteinfrom a newly isolated Ochrobactrum anthropi CTS-325

CHENG Yangjian , XIE Yongming , ZHENG Jing , WU Zhaoxian , CHEN Zhi , MA Xiaoyan , LI Bin , LIN Zhang


Received January 16, 2009,Revised May 06, 2009, Accepted , Available online

Volume 21,2009,Pages 1673-1678

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A Gram-negative, chromium(VI) tolerant and reductive strain CTS-325, isolated from a Chinese chromate plant, was identified as Ochrobactrum anthropi based on its biochemical properties and 16S rDNA sequence analysis. It was able to tolerate up to 10 mmol/L Cr(VI) and completely reduce 1 mmol/L Cr(VI) to Cr(III) within 48 h. When the strain CTS-325 was induced with Cr(VI), a protein increased significantly in the whole cell proteins. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis revealed that this protein was a superoxide dismutase (SOD) homology. The measured superoxide dismutase activity was 2694 U/mg after three steps of purification. The SOD catalyzes the dismutation of the superoxide anion (O2 .??) into hydrogen peroxide and molecular oxygen. This protein is considered to be one of the most important anti-oxidative enzymes for O. anthropi as it allows the bacterium to survive high oxygen stress environments, such as the environment produced during the reduction process of Cr(VI).

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