Mechanisms of gold biomineralization in the bacterium Cupriavidus metallidurans
Mechanisms of gold biomineralization in the bacterium Cupriavidus metallidurans
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DOI：
10.1073/pnas.0904583106
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发表时间：
2009-10-20
影响因子：
11.1
通讯作者：
Brugger, Joel
中科院分区：
文献类型：
--
作者：
Reith, Frank;Etschmann, Barbara;Brugger, Joel
虽然微生物作为地球表面条件下金属流动性和矿物形成的主要驱动力的作用现在被广泛接受，但次生金（Au）的形成通常归因于非生物过程。在这里，我们报告说，生物矿化的Au纳米粒子的亲金属细菌Cupriavidus metallidurans CH 34的结果是Au调节基因表达导致的能量依赖性还原沉淀的有毒Au（III）-络合物。C.在Au颗粒上形成生物膜的metallidurans从溶液中快速积累Au（III）-络合物。体和微束同步辐射X射线分析表明，细胞Au积累耦合到Au（I）-S络合物的形成。该过程促进了Au毒性和C. metallidurans通过诱导氧化应激和金属抗性基因簇（包括Au特异性操纵子）来反应，以促进细胞防御。因此，Au解毒通过Au-络合物的流出、还原和可能的甲基化的组合介导，导致形成Au（I）-C-化合物和纳米颗粒Au-0。在Au颗粒上的细菌生物膜中观察到类似的颗粒，表明细菌积极地促进表面环境中Au颗粒的形成。对Au的特异性遗传反应的识别为生物勘探和生物处理工具的开发开辟了道路。
While the role of microorganisms as main drivers of metal mobility and mineral formation under Earth surface conditions is now widely accepted, the formation of secondary gold (Au) is commonly attributed to abiotic processes. Here we report that the biomineralization of Au nanoparticles in the metallophillic bacterium Cupriavidus metallidurans CH34 is the result of Au-regulated gene expression leading to the energy-dependent reductive precipitation of toxic Au(III)-complexes. C. metallidurans, which forms biofilms on Au grains, rapidly accumulates Au(III)-complexes from solution. Bulk and microbeam synchrotron X-ray analyses revealed that cellular Au accumulation is coupled to the formation of Au(I)-S complexes. This process promotes Au toxicity and C. metallidurans reacts by inducing oxidative stress and metal resistances gene clusters ( including a Au-specific operon) to promote cellular defense. As a result, Au detoxification is mediated by a combination of efflux, reduction, and possibly methylation of Au-complexes, leading to the formation of Au(I)-C-compounds and nanoparticulate Au-0. Similar particles were observed in bacterial biofilms on Au grains, suggesting that bacteria actively contribute to the formation of Au grains in surface environments. The recognition of specific genetic responses to Au opens the way for the development of bioexploration and bioprocessing tools.