RII Track-4: Physiology of Sulfate-Reducing Bacteria under Energy-Limiting conditions

细菌有能力在能量有限的条件下存活很长一段时间，这在自然环境中很常见。为了了解能量限制的基本方面，可以在培养基中研究细菌数月至数年，而不向培养基补充能量。本项目旨在研究硫酸盐还原菌（SRB）的长期培养，该细菌在缺氧环境中驱动硫和碳的生物地球化学循环。该研究将研究SRB细胞和外膜的完整性，并量化代谢过程，以获得SRB长期生存的生理学见解。该项目将推进微生物在缺氧环境中长期生存的基础知识。该项目对于受SRB影响的经济上至关重要的过程也很重要，例如铁基础设施的腐蚀，废水处理和金属污染环境的生物修复。该奖学金将通过向研究生课程提供高分辨率成像讲座来改善STEM教育，2)PI的研究能力，以及3)内华达大学拉斯维加斯分校的研究基础设施。该项目的目标是表征硫酸盐还原细菌的延长生命周期，并破译硫化物矿物结壳在其延长生命周期中保持SRB生存能力的作用。我们的初步实验表明，矿物包壳细菌可以存活数年，并在新鲜培养基中再生，而类似年龄的无包壳细胞不能再生。本研究将对无矿物质和包壳硫酸盐还原菌在长期固定期的代谢和生理变化进行表征。它还将确定细胞表面矿物结壳形成的早期步骤和细胞在新鲜培养基中再生时矿物结壳去除的步骤。透射电子显微镜（TEM）将用于对细胞及其膜和细胞壁的完整性进行高分辨率成像，而电子衍射将用于获取细胞周围形成的矿物相的信息。超分辨率荧光显微镜（iPALM）将用于定位和定量代谢过程，如新蛋白合成、质子梯度形成和三磷酸腺苷合成在无矿物和包覆SRB的延长生命周期。这个项目将使人们更好地了解硫酸盐还原细菌的长期生存和硫化物矿物在保持SRB长期生存能力方面的作用，这有助于这些矿物的形成。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Bacteria have the ability to survive long periods of time under energy-limiting conditions, common in natural environments. To understand the fundamental aspects of energy limitation, bacteria can be studied in cultures for months to years without re-supplying the medium with energy sources. This project aims to study long-term cultures of sulfate-reducing bacteria (SRB), which drive the sulfur and carbon biogeochemical cycles in anoxic environments. The proposed research will investigate the integrity of the cell and outer membranes of SRB and quantify metabolic processes to gain physiological insights into the long-term survival of SRB. This project will advance fundamental knowledge about long-term survival of microorganisms in anoxic environments. The project is also of importance for the economically vital processes that are influenced by SRB, such as the corrosion of iron infrastructure, wastewater treatment, and bioremediation of metal contaminated environments. This fellowship will improve 1) STEM education through the delivery of lectures on high-resolution imaging to graduate courses, 2) the research capacity of the PI, and 3) the research infrastructure at the University of Nevada, Las Vegas. The goals of this project are to characterize the extended life cycle of sulfate-reducing bacteria and to decipher the role of sulfide mineral crusts in preserving the viability of SRB in their extended life cycle. Our preliminary experiments have indicated that mineral-encrusted bacteria can be preserved alive for several years and regrow in fresh medium when non-encrusted cells of similar age do not regrow. The proposed research will characterize the metabolic and physiological changes in mineral-free and encrusted sulfate-reducing bacteria in the long-term stationary phase. It will also identify the early steps of mineral crust formation at the surface of cells and the steps of mineral crust removal when cells regrow in fresh medium. Transmission electron microscopy (TEM) will be used to image the integrity of the cells and their membranes and cell wall at high resolution, while electron diffraction will be used to gain information about the mineral phases forming around cells. Super resolution fluorescence microscopy (iPALM) will be used to localize and quantify metabolic processes such as new protein synthesis, proton gradient formation and adenosine triphosphate synthesis during the extended life cycle of mineral-free and encrusted SRB. This project will lead to a better understanding of long-term survival of sulfate-reducing bacteria and of the role of sulfide minerals in preserving long-term viability of SRB, which contribute to the formation of those minerals.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.