在铜离子（Cu2+）刺激下，芽孢杆菌属ES 29的无细胞提取物对六价铬进行体外还原。
In vitro reduction of hexavalent chromium by a cell-free extract of Bacillus sp. ES 29 stimulated by Cu2+.
作者信息
Camargo F A O, Okeke B C, Bento F M, Frankenberger W T
机构信息
Department of Environmental Science, University of California, Riverside, CA 92521, USA.
出版信息
Appl Microbiol Biotechnol. 2003 Oct;62(5-6):569-73. doi: 10.1007/s00253-003-1291-x. Epub 2003 Apr 3.
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 Km of 7.09 microM and a Vmax of 0.171 micromol min(-1) mg(-1) protein. Mercury inhibited the enzyme, but not competitively, with a Vmax of 0.143 micromol min(-1) mg(-1) protein, a Km of 7.07 microM and a Ki of 1.58 microM. This study characterizes the enzymatic reduction of Cr(VI) by Bacillus sp. ES 29 which can be used for the bioremediation of chromate.
从土壤中分离出的耐铬细菌（CRB）可用于减少受污染环境中的有毒六价铬（Cr(VI)）。本研究使用从受重铬酸盐污染的土壤中分离出的CRB的无细胞提取物（CFE）评估了六价铬的体外还原情况。通过16S rRNA基因序列同源性鉴定出一种能显著还原Cr(VI)的分离株ES 29为芽孢杆菌属物种。该分离株在有氧条件下以NADH作为电子供体还原Cr(VI)，并产生一种受铜（Cu2+）刺激的可溶性Cr(VI)还原酶。该细菌分离株的CFE在6小时内还原了50%的Cr(VI)。CFE的Cr(VI)还原活性的Km为7.09微摩尔，Vmax为0.171微摩尔·分钟-1·毫克-1蛋白质。汞抑制该酶，但不是竞争性抑制，其Vmax为0.143微摩尔·分钟-1·毫克-1蛋白质，Km为7.07微摩尔，Ki为1.58微摩尔。本研究对芽孢杆菌属ES 29对Cr(VI)的酶促还原进行了表征，该菌株可用于铬酸盐的生物修复。
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