Thioredoxin is involved in hexavalent chromium reduction in Streptomyces violaceoruber strain LZ-26-1 isolated from the Lanzhou reaches of the Yellow River
Thioredoxin is involved in hexavalent chromium reduction in Streptomyces violaceoruber strain LZ-26-1 isolated from the Lanzhou reaches of the Yellow River
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硫氧还蛋白参与黄河兰州河段分离的紫色链霉菌LZ-26-1菌株六价铬的还原
DOI：
10.1016/j.ibiod.2014.07.013
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发表时间：
2014-10-01
影响因子：
4.8
通讯作者：
Li, Xiangkai
中科院分区：
文献类型：
--
作者：
Chen, Zhengjun;Zou, Luming;Li, Xiangkai
六价铬[Cr(VI)]是黄河兰州河段的主要环境污染物之一，放线菌对该地区Cr（VI）的生物修复尚显匮乏。本研究从兰州河段分离到20株能在淀粉酪蛋白（SC）琼脂板上抵抗1.2 mM Cr（VI）的放线菌。根据16S rRNA序列数据，16株菌株属于Streptomyces，另外4株菌株属于Gordonia、Nocardiopsis、Nocardia和cellulosimicroum。其中一株与紫链霉菌（Streptomyces violaceoruber）亲缘关系较近的菌株LZ-26-1具有显著的Cr（VI）还原能力。在SC液体介质中，14h可将0.6 mM Cr（VI）还原为92.86%的三价铬[Cr(III)]，还原Cr（VI）的最佳温度和pH分别为28℃和7.0℃。透射电镜图像显示，铬在细胞内沉淀。在静息细胞和粗铬酸盐还原酶实验中，以NADPH作为电子供体刺激菌株LZ-26-1的Cr（VI）还原，Cd2+处理抑制Cr（VI）还原。此外，硫氧还蛋白操纵子由三个编码硫氧还蛋白、硫氧还蛋白还原酶（NADPH）和一种可能的膜蛋白的基因组成，在Cr（VI）处理下上调。这些结果表明LZ-26-1可能通过硫氧还蛋白途径降低Cr（VI）。(C) 2014 Elsevier Ltd.版权所有。
Hexavalent chromium [Cr(VI)] is one of the major environmental contaminants in the Lanzhou reaches of the Yellow River, and actinomycetes' Cr(VI) bioremediation within this area is still scarce. In the present study, twenty actinomycete strains were isolated from the Lanzhou reaches which could resist 1.2 mM Cr(VI) on Starch-Casein (SC) agar plates. Based on the 16S rRNA sequence data, sixteen strains belong to Streptomyces and four other strains belong to Gordonia, Nocardiopsis, Nocardia and Cellulosimicrobium. One strain named LZ-26-1 which is closely related to Streptomyces violaceoruber demonstrated a notable ability of Cr(VI) reduction. It could reduce 92.86% of the 0.6 mM Cr(VI) to trivalent chromium [Cr(III)] in SC liquid medium in 144 h. The optimum temperature and pH were 28 degrees C and 7.0 for Cr(VI) reduction. Transmission electron microscopy images showed that chromium was precipitated inside the cells. In resting cells and crude chromate reductase assays, strain LZ-26-1's Cr(VI) reduction was stimulated when NADPH was used as an electron donor and Cd2+ treatment inhibited Cr(VI) reduction. Furthermore, thioredoxin operon, which consists of three genes encoding a thioredoxin, thioredoxin reductase (NADPH) and a possible membrane protein, was upregulated by Cr(VI) treatment. These results suggested that LZ-26-1 might utilize a thioredoxin pathway to reduce Cr(VI). (C) 2014 Elsevier Ltd. All rights reserved.