Evaluation of In vitro Cr(VI) reduction potential in cytosolic extracts of three indigenous Bacillus sp isolated from Cr(VI) polluted industrial landfill
Evaluation of In vitro Cr(VI) reduction potential in cytosolic extracts of three indigenous Bacillus sp isolated from Cr(VI) polluted industrial landfill
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DOI：
10.1016/j.biortech.2007.12.046
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发表时间：
2008-09-01
影响因子：
11.4
通讯作者：
Madamwar, Datta
中科院分区：
文献类型：
--
作者：
Desai, Chirayu;Jain, Kunal;Madamwar, Datta
从受Cr（VI）污染的垃圾填埋场中分离到3株高效Cr（VI）还原菌，并对其进行了体外Cr（VI）还原特性的研究。16 S rRNA基因序列分析表明，G1 DM 20、G1 DM 22和G1 DM 64分别与蜡状芽孢杆菌、梭形芽孢杆菌和球形芽孢杆菌亲缘关系较近。所有芽孢杆菌的悬浮培养物在30小时内表现出超过85%的1000 μ M Cr（VI）的还原。芽孢杆菌属G1 DM 22的悬浮培养物表现出连续还原100 μ M Cr（VI）的能力，最多可连续7次输入。从每一个芽孢杆菌的透化细胞和无细胞提取物的测定表明，六价铬还原酶活性主要与细胞的可溶性部分和组成型表达。芽孢杆菌G1 DM 20和G1 DM 22的无细胞提取物的Cr（VI）还原在30 ℃和pH 7下最大，而芽孢杆菌G1 DM 64在pH 6下表现出最大的Cr（VI）还原。添加1 mM的NADH增强了所有三个菌株的无细胞提取物中的Cr（VI）还原酶活性。在所有三个测试菌株，芽孢杆菌属G1 DM 22的粗无细胞提取物表现出最快的Cr（VI）的还原速率与100 μ M的Cr（VI）在100分钟内完全还原。在芽孢杆菌属G1 DM 22的铬酸盐还原酶活性的表观Km和V-最大值被确定为200 μ M的Cr（VI）和5.5 μ mol/min/mg蛋白质，分别。除Hg 2+和Ag+外，所有分离株的无细胞提取物中的Cr（VI）还原酶活性在所测试的不同金属离子存在下均保持稳定。(C)2007爱思唯尔有限公司版权所有。
Three efficient Cr(VI) reducing bacterial strains were isolated from Cr(VI) polluted landfill and characterized for in vitro Cr(VI) reduction. Phylogenetic analysis using 16S rRNA gene sequencing revealed that the newly isolated strains G1DM20, G1DM22 and G1DM64 were closely related to Bacillus cereus, Bacillus fusiformis and Bacillus sphaericus, respectively. The suspended cultures of all Bacillus sp. exhibited more than 85% reduction of 1000 mu M Cr(VI) within 30 h. The suspended culture of Bacillus sp. G1DM22 exhibited an ability for continuous reduction of 100 mu M Cr(VI) up to seven consecutive inputs. Assays with the permeabilized cells and cell-free extracts from each of Bacillus sp. demonstrated that the hexavalent chromate reductase activity was mainly associated with the soluble fraction of cells and expressed constitutively. The Cr(VI) reduction by the cell-free extracts of Bacillus sp. G1DM20 and G1DM22 was maximum at 30 degrees C and pH 7 whereas, Bacillus sp. G1DM64 exhibited maximum Cr(VI) reduction at pH 6. Addition of 1 mM NADH enhanced the Cr(VI) reductase activity in the cell-free extracts of all three isolates. Amongst all three isolates tested, crude cell-free extracts of Bacillus sp. G1DM22 exhibited the fastest Cr(VI) reduction rate with complete reduction of 100 mu M Cr(VI) within 100 min. The apparent K-m and V-max of the chromate reductase activity in Bacillus sp. G1DM22 were determined to be 200 mu M Cr(VI) and 5.5 mu mol/min/mg protein, respectively. The Cr(VI) reductase activity in cell-free extracts of all the isolates was stable in presence of different metal ions tested except Hg2+ and Ag+. (C) 2007 Elsevier Ltd. All rights reserved.