白银市稀土矿分离到一株可以高效还原六价铬的枯草芽孢杆菌

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	白银市稀土矿分离到一株可以高效还原六价铬的枯草芽孢杆菌
Alternative Title	A BACILLUS SUBTILIS CAN REDUCE HEXAVALENT CHROMIUM TO TRIVALENT AND AN NFRA GENE IS INVOLVED IN THE REDUCTION
	郑喆
Thesis Advisor	李祥锴
	2015-05-18
Degree Grantor	兰州大学
Place of Conferral	兰州
Degree Name	硕士
Keyword	枯草芽孢杆菌生物修复 nfrA 六价铬稀土矿白银市
Abstract	坐落于中国甘肃省中部位于黄河中上游的白银市重金属污染情况非常严重。由于稀有金属的冶炼，其中六价铬的排放量也远远超过了国家的排放标准。我们从白银市的重金属污染区采样，从中分离到了一株革兰氏阴性的短杆状的枯草芽孢杆菌BYCr-1。BYCr-1在需氧条件下，它具有非常高的六价铬抗性和很强的六价铬还原能力。16S rRNA分析显示它和Bacillus subtilis subsp. subtilis str. SC-8具有98.6%的相似度。还原实验表明BYCr-1可以在48小时内完全还原M9培养基中0.2mM的六价铬。透射电镜结果显示可见的三价铬沉淀存在于细胞外和细胞内。通过生物信息学的方法，我们找到了BYCr-1中可能参与到六价铬还原中的基因nfrA。实时定量PCR分析结果显示它在六价铬的压力下表达上调5.3倍。我们将nfrA外源表达到大肠杆菌中，结果发现nfrA可以提高大肠杆菌还原六价铬的能力。我们的实验结果显示，BYCr-1具有很高的六价铬抗性和还原能力。由此说明BYCr-1可以作为处理白银市重金属污染的生物修复的工具。实验结果还表明，nfrA基因参与到BYCr-1还原六价铬中。
Other Abstract	Baiyin city, which is located upstream of the Yellow River and in the central part of Gansu province, China, is severely contaminated by heavy metals such as chromium. A Gram-positive bacterium BYCr-1 capable of reducing hexavalent chromium (Cr(VI)) to trivalent (Cr(III)) aerobically was isolated from a rare-earth ore in Baiyin, Gansu, China. 16S rRNA analysis revealed that it was closely related to Bacillus subtilis. It can reduce 0.2 mM Cr(VI) to Cr(III) in M9 medium after 48 hours incubation. Transmission electron microscopy (TEM) image showed that Cr(III) precipitates were located both inside and outside the cells. An nfrA gene was upregulated by 5.3 folds upon Cr(VI) treatment. Furthermore, E. coli-NfrA demonstrated elevated chromate- reducing ability. Our results indicate that BYCr-1 is able to resist and reduce high concentrations of Cr(VI), which makes it a potentially suitable candidate for bioremediation of Cr(VI) contamination. This study also reveals that nfrA confers Cr(VI)-reducing ability in Bacillus subtilis.
URL	查看原文
Language	中文
Document Type	学位论文
Identifier	https://ir.lzu.edu.cn/handle/262010/221781
Collection	生命科学学院
Recommended Citation GB/T 7714	郑喆. 白银市稀土矿分离到一株可以高效还原六价铬的枯草芽孢杆菌[D]. 兰州. 兰州大学,2015.

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