六价铬还原细菌Bacillus cereus S5.4还原机理及酶学性质研究  

Mechanisms and Enzymatic Characters of Hexavalent Chromium Reduction by Bacillus cereus S5.4

作　　者：肖伟[1] 王磊[2] 李倬锴[1] 张思维[1] 任大明[1] 

机构地区：[1]复旦大学遗传工程国家重点实验室,上海200433 [2]同济大学环境科学与工程学院,上海200092

出　　处：《环境科学》2008年第3期751-755,共5页Environmental Science

基　　金：国家自然科学基金项目(50130030)

摘　　要：从宝钢电镀污泥中分离得到1株六价铬还原细菌Bacillus cereus S5.4,在液体LB培养基中培养72 h完全还原2 mmol/LCr^6＋.测定该菌株六价铬还原后细胞内外六价铬和总铬浓度,检测细胞各组分六价铬还原能力,并结合扫描电镜分析六价铬还原前后细胞形态的变化.结果表明,细菌的细胞壁膜能阻止六价铬进入细胞,是六价铬发生还原的主要场所,其通透性的改变将影响六价铬还原酶的作用;该菌株六价铬还原酶为非分泌型,在细菌细胞内侧发生作用.测定六价铬还原酶活性和稳定性：其最适温度范围25-37℃,最适pH 7,Cu^2＋有增强六价铬还原酶活性的作用;在37℃,该菌株六价铬还原酶Km为125.61μmol/L,Vmax为7.68 nmol/（min·mg）.A strain of bacteria identified as Bacillus cereus $5.4, which was isolated from the electroplating sludge of Baosteel Corporation, Shanghai, was able to completely reduce 2 mmol/L Cr^6＋ in LB liquid after 72 hours. Experiments on concentrations of hexavalent and total chromium inside and outside bacterial cells after hexavalent chromium reduction, and hexavalent chromium reduction abilities of different cellular components, and SEM analysis of cellular morphology before and after hexavalent chromium reduction, showed that cellular walls and membranes, which were able to prevent hexavalent chromium out from living cells, were the main sites where hexavalent chromium reduction took place, and changes of their permeability would take effect on the function of hexavalent chromium reductase. The reductase was non- secretive and took effect on the inner side of living cells. Determination of the activity and stability of hexavalent chromium reductase showed that the optimal temperature range and pH of the reductase was 25 - 37℃ and pH 7, respectively. Cu^2＋ had some effect on the promotion of reductase activity. At the temperature of 37℃, Km and Vmax of the reductase was 125.61 μmol/L and 7.68 nmol/（min· mg）, respectively.

关 键 词：Bacilluscereus 六价铬 还原酶 酶动力学曲线 

分 类 号：X172[环境科学与工程—环境科学]