Metal Resistance and Lithoautotrophy in the Extreme Thermoacidophile Metallosphaera sedula
Metal Resistance and Lithoautotrophy in the Extreme Thermoacidophile Metallosphaera sedula
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DOI：
10.1128/jb.01413-12
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发表时间：
2012-12-01
影响因子：
3.2
通讯作者：
Blum, Paul
中科院分区：
文献类型：
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作者：
Maezato, Yukari;Johnson, Tyler;Blum, Paul
古细菌如seula Metallosphaera是嗜热的岩石自养生物，它们生活在异常酸性和富含金属的环境中。这些特性被认为是它们对碱金属和贵金属生物浸出的工业重要性的基础。本研究采用遗传方法研究了原生铜矿黄铜矿（CuFeS2）生物转化过程中金属抗性与岩石自养的具体关系。在本研究中，建立了一个sedula的遗传系统，以研究限制黄铜矿生物浸出的参数。通过铜敏感突变体的跨种互补，证实了冬冬铜rta操纵子的功能作用。利用靶向重组使M. sedula铜外排蛋白（copA）基因失活，降低了金属抗性并消除了黄铜矿的生物浸出。相比之下，具有较高金属抗性的自发性M. sedula突变体（CuR1）在不影响化学异养生长的情况下以更快的速度转化黄铜矿。CuR1的蛋白质组学分析发现了多效性变化，包括具有aaa - atp酶基序的转运蛋白丰度的改变。不溶性碳酸盐矿物辉石（BaCO3）的加入进一步促进了黄铜矿的岩性侵蚀，表明碳是一个限制因素。由于这两种矿物类型都被积极定植，因此表面粘附种群之间的能量和碳的合作交换可能会增强金属浸出。遗传学方法通过加强对嗜热岩石自养机理的认识，为提高金属生物浸出效率提供了新的手段。
Archaea such as Metallosphaera sedula are thermophilic lithoautotrophs that occupy unusually acidic and metal-rich environments. These traits are thought to underlie their industrial importance for bioleaching of base and precious metals. In this study, a genetic approach was taken to investigate the specific relationship between metal resistance and lithoautotrophy during biotransformation of the primary copper ore, chalcopyrite (CuFeS2). In this study, a genetic system was developed for M. sedula to investigate parameters that limit bioleaching of chalcopyrite. The functional role of the M. sedula copRTA operon was demonstrated by cross-species complementation of a copper-sensitive Sulfolobus solfataricus copR mutant. Inactivation of the gene encoding the M. sedula copper efflux protein, copA, using targeted recombination compromised metal resistance and eliminated chalcopyrite bioleaching. In contrast, a spontaneous M. sedula mutant (CuR1) with elevated metal resistance transformed chalcopyrite at an accelerated rate without affecting chemoheterotrophic growth. Proteomic analysis of CuR1 identified pleiotropic changes, including altered abundance of transport proteins having AAA-ATPase motifs. Addition of the insoluble carbonate mineral witherite (BaCO3) further stimulated chalcopyrite lithotrophy, indicating that carbon was a limiting factor. Since both mineral types were actively colonized, enhanced metal leaching may arise from the cooperative exchange of energy and carbon between surface-adhered populations. Genetic approaches provide a new means of improving the efficiency of metal bioleaching by enhancing the mechanistic understanding of thermophilic lithoautotrophy.