从铬污染土壤中分离出的耐铬细菌的细胞游离提取物对体外六价铬还原作用的比较。
Comparison of in vitro Cr(VI) reduction by CFEs of chromate resistant bacteria isolated from chromate contaminated soil.
作者信息
Sarangi Abhipsa, Krishnan Chandraraj
机构信息
Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600 036, India.
出版信息
Bioresour Technol. 2008 Jul;99(10):4130-7. doi: 10.1016/j.biortech.2007.08.059. Epub 2007 Oct 24.
Chromate resistant and reducing strains were isolated from chromium contaminated soil and identified as Bacillus sp. (KCH2 and KCH3), Leucobacter sp. (KCH4) and Exiguobacterium sp. (KCH5). KCH3 and KCH4 showed higher Cr(VI) tolerance (2 mM) and Cr(VI) reduction (1.5 mM) than KCH5 (1.5 mM and 0.75 mM, respectively). Cr(VI) reduction by CFEs of KCH3 and KCH4 showed NAD(P)H dependence, optimum activity at pH 5.5, low K(m) (45-55 microM) and substrate inhibition by Cr(VI) (>75 microM), whereas that of KCH5 showed NADH dependence, pH optimum at 6.0, high K(m) (200 microM) and no inhibition by Cr(VI). Cr(VI) reduction was optimum at 35 degrees C for CFEs of KCH3 and KCH5 and 30 degrees C for that of KCH3. Cr(VI) reduction by CFEs of all the strains were inhibited by Hg(2+) and enhanced by Cu(2+). Activity enhancement by Cu(2+) was more predominant (290%) for KCH4. The characterization of Cr(VI) reduction by CFEs of chromate resistant isolates of different genera is useful for development of Cr(VI) bioremediation.
从铬污染土壤中分离出耐铬和具有还原能力的菌株，并鉴定为芽孢杆菌属（KCH2和KCH3）、勒克氏菌属（KCH4）和微小杆菌属（KCH5）。KCH3和KCH4对Cr(VI)的耐受性（2 mM）和Cr(VI)还原能力（1.5 mM）高于KCH5（分别为1.5 mM和0.75 mM）。KCH3和KCH4的无细胞提取物对Cr(VI)的还原表现出对NAD(P)H的依赖性，在pH 5.5时活性最佳，低米氏常数（45 - 55 microM）且受Cr(VI)（>75 microM）的底物抑制，而KCH5的无细胞提取物对Cr(VI)的还原表现出对NADH的依赖性，最适pH为6.0，高米氏常数（200 microM）且不受Cr(VI)抑制。KCH3和KCH5的无细胞提取物对Cr(VI)的还原在35℃时最佳，KCH4的在30℃时最佳。所有菌株的无细胞提取物对Cr(VI)的还原均受Hg(2+)抑制，受Cu(2+)增强。Cu(2+)对KCH4的活性增强作用更显著（290%）。不同属的耐铬分离株无细胞提取物对Cr(VI)还原的特性研究有助于Cr(VI)生物修复技术的开发。
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