In Vivo Characterization of Bacteria-mediated Extracellular Reduction of Chromium

细菌介导的细胞外铬还原的体内表征

• 批准号: 7572738
• 负责人: H Peter Lu
• 金额: $ 33.89万
• 依托单位: BOWLING GREEN STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-13 至 2011-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7572738
• 关键词: Bacteria; Bioremediations; Cell surface; Chromium; Complex; Cytochrome c Group; Cytochromes; Electron Microscopy; Goals; Gold; Health; Human; Image; In Situ; In Vitro; Individual; Iron; Kinetics; Location; Measurement; Measures; Mediating; Metals; Methods; Microscopy; Molecular; Oxides; Oxidoreductase; Play; Resolution; Role; Scanning; Scanning Electron Microscopy; Science; Shewanella; Solutions; Surface; Testing; Toxic effect; Water; base; chromium hexavalent ion; extracellular; hematite; in vivo; nanometer; nanoscale; nanosized; oxidation; particle; research study; superfund site

DESCRIPTION (provided by the applicant): Hexavalent chromium[Cr(VI)]exists at the Superfund sites where it poses major health concerns to humans. Bacteria-mediated in situ transformation of water soluble and toxic Cr(VI) to less soluble/toxic Cr(III) represents a promising method to contain and treat Cr(VI). However, the molecular mechanisms by which bacteria reduce Cr(VI) remain undetermined. Reduction of Cr(VI) by dissimilatory iron (Fe) reducing bacterium Shewanella oneidensis results in formation of nano-sized Cr(III) particles on the cell surfaces. We hypothesize that cell surface-exposed cytochromes MtrC and OmcA of S. oneidensis are involved in the formation of Cr(III) by reducing Cr(VI) directly as Cr(VI) terminal reductases and indirectly as Fe(III) oxide terminal reductases to produce Fe(II) that in turn reduces Cr(VI). We plan to use nanoscale AFM correlated SERS imaging microscopy (AFM-CSIM) developed by us along with other methods to test our hypothesis. AFM-CSIM can simultaneously determine the locations of cytochromes and nano-sized metal particles as well as their oxidation states on the bacterial surfaces at nanometer-resolution. Co-localization of MtrC and OmcA with nano-sized Cr(III) and Fe(III) particles by AFM-CSIM will provide direct evidences to support our hypothesis. Other approaches (e.g. immuno-gold localization with scanning electron microscopy and the measurements of Cr(VI) reductase activity of purified MtrC and OmcA) will be used to validate the AFM-CSIM results. Successful completion of this project will help not only achieve our long-term goal of understanding the molecular mechanisms by which bacteria reduce Cr(VI), but also develop science-based solutions to mitigate the toxic effects of Cr(VI) at the Superfund sites.

描述（由申请人提供）： 超级基金所在地存在六价铬[Cr(VI)]，对人类造成重大健康问题。细菌介导的将水溶性且有毒的 Cr(VI) 原位转化为难溶性/毒性较小的 Cr(III) 是一种有前景的遏制和处理 Cr(VI) 的方法。然而，细菌还原 Cr(VI) 的分子机制仍不清楚。异化铁 (Fe) 还原细菌希瓦氏菌 (Shewanella oneidensis) 还原 Cr(VI) 会导致细胞表面形成纳米尺寸的 Cr(III) 颗粒。我们假设 S. oneidensis 细胞表面暴露的细胞色素 MtrC 和 OmcA 通过直接还原 Cr(VI) 作为 Cr(VI) 末端还原酶和间接还原为 Fe(III) 氧化物末端还原酶来参与 Cr(III) 的形成，从而产生 Fe(II)，进而还原 Cr(VI)。我们计划使用我们开发的纳米级 AFM 相关 SERS 成像显微镜 (AFM-CSIM) 以及其他方法来检验我们的假设。 AFM-CSIM 可以以纳米分辨率同时确定细胞色素和纳米金属颗粒的位置及其在细菌表面的氧化态。 AFM-CSIM 对 MtrC 和 OmcA 与纳米级 Cr(III) 和 Fe(III) 颗粒的共定位将为支持我们的假设提供直接证据。其他方法（例如使用扫描电子显微镜进行免疫金定位以及测量纯化的 MtrC 和 OmcA 的 Cr(VI) 还原酶活性）将用于验证 AFM-CSIM 结果。该项目的成功完成不仅有助于实现我们了解细菌还原 Cr(VI) 的分子机制的长期目标，而且有助于开发基于科学的解决方案，以减轻 Superfund 站点中 Cr(VI) 的毒性作用。