In vitro reduction of hexavalent chromium by a cell-free extract of Bacillus sp ES 29 stimulated by Cu2+
In vitro reduction of hexavalent chromium by a cell-free extract of Bacillus sp ES 29 stimulated by Cu2+
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DOI：
10.1007/s00253-003-1291-x
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发表时间：
2003-10-01
影响因子：
5
通讯作者：
Frankenberger, WT
中科院分区：
文献类型：
--
作者：
Camargo, FAO;Okeke, BC;Frankenberger, WT
从土壤中分离的耐铬细菌（CRB）可用于降低污染环境中的有毒Cr（VI）。本研究评估了在体外还原六价铬使用无细胞提取物（CFE）的CRB分离出的土壤中重铬酸盐污染。通过16 S rRNA基因序列同源性鉴定了一个显著降低Cr（VI）的分离株ES 29为芽孢杆菌属。该分离物在有氧条件下还原Cr（VI），使用NADH作为电子供体，并产生可溶性Cr（VI）还原酶，其由铜（Cu 2+）刺激。该菌株的CFE在6 h内可将Cr（VI）还原50%。CFE的Cr（VI）还原活性的Km为7.09 μ M，Vmax为0.171 μ mol min（-1）mg（-1）protein。汞抑制酶，但不是竞争性的，V-max为0.143 μ mol min（-1）mg（-1）protein，K-m为7.07 μ M，K-i为1.58 μ M。研究了芽孢杆菌ES 29对Cr（VI）的酶促还原作用，并将其应用于铬酸盐的生物修复。
Chromium-resistant bacteria (CRB) isolated from soils can be used to reduce toxic Cr(VI) from contaminated environments. This study assessed in vitro reduction of hexavalent Cr using a cell-free extract (CFE) of CRB isolated from soil contaminated with dichromate. One isolate, ES 29, that substantially reduced Cr(VI) was identified as a Bacillus species by 16S rRNA gene-sequence homology. The isolate reduced Cr(VI) under aerobic conditions, using NADH as an electron donor and produced a soluble Cr(VI)-reducing enzyme stimulated by copper (Cu2+). The CFE of the bacterial isolate reduced 50% of Cr(VI) in 6 h. The Cr(VI)-reduction activity of the CFE had a K-m of 7.09 muM and a V-max of 0.171 mumol min(-1) mg(-1) protein. Mercury inhibited the enzyme, but not competitively, with a V-max of 0.143 mumol min(-1) mg(-1) protein, a K-m of 7.07 muM and a K-i of 1.58 muM. This study characterizes the enzymatic reduction of Cr(VI) by Bacillus sp. ES 29 which can be used for the bioremediation of chromate.