Sustainable bioproduction using phototrophic extracellular electron uptake

一些细菌能够利用电力和光能来固定二氧化碳，并最终用于可再生的、碳中和的、碳封存的生产某些高价值化合物。该项目的总体目标是更好地了解这种生物生产过程，并设计细菌，将这种过程用于生物塑料和生物燃料的生产。该项目将为高中、本科和研究生阶段的学生创造沉浸式研究机会。微生物还原氧化反应驱动生物圈中的物质和能量流动。大多数微生物使用可溶性电子供体和受体，但有些微生物使用固相导电物质。潜在的微生物过程被称为细胞外电子转移（EET）。在EET过程中，电子流的方向可以是向外的，其中固相导电物质通过还原性EET被微生物还原；或入站，固相导电物质通过细胞外电子摄取（EEU）被氧化。虽然还原性eet的研究由来已久，但EEU最近才崭露头角，代表了微生物生物地球化学的范式转变。这是因为具有eeu能力的微生物可以氧化丰富的固相导电物质，如矿物质，以供微生物生长。许多微生物可以进行EEU，但只有一小部分微生物可以进行光养性EEU。这种特殊的新陈代谢利用来自固体导电矿物或其替代品（平衡电极）的光能和电子来固定二氧化碳。因此，光养型eeu代表了一种新的代谢工程，用于可持续的、碳中和的到碳封存的生物生产。为了了解光养- eeu在环境中的普遍存在，并充分实现其生物工程潜力，必须解决几个基本的知识空白。这些包括深入表征电子输入模块及其调节；电子转移途径和细胞电子下沉。利用多组学和跨学科的方法，该项目旨在填补这些知识空白，以获得淡水微生物，红假单胞菌palustris和海洋微生物Rhodovulum sulfidophilum中的光营养性eeu的系统级理解。该项目将利用合成生物学、代谢工程学和材料科学，利用光养型eeu提高生物塑料和生物燃料的可持续生产。总之，该项目将扩大我们对光养- eeu的理解，并探索利用具有光养- eeu能力的微生物-古红假单胞菌生产可持续生物产品。该项目还将吸引不同教育水平的学生参与可持续发展研究。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。

Some bacteria are capable of using electricity and energy from light to fix carbon dioxide and ultimately for renewable, carbon-neutral to carbon-sequestering production of certain high value compounds. The overall goal of this project is to better understand this bioproduction process and to engineer bacteria to use this process for bioplastic and biofuel production. This project will create immersive research opportunities for students at the high school, undergraduate and graduate school levels. Microbial reduction-oxidation reactions drive matter and energy flow in the biosphere. Most microbes use soluble electron donors and acceptors, but some use solid-phase conductive substances. The underlying microbial process is called extracellular electron transfer (EET). The directionality of electron flow during EET can be either outbound, where solid-phase conductive substances are microbially reduced via reductive-EET; or inbound, where solid-phase conductive substances are oxidized via extracellular electron uptake (EEU). While reductive-EET is long studied, EEU has come to fore recently, and represents a paradigm shift in microbial biogeochemistry. This is because EEU-capable microbes can oxidize abundant solid-phase conductive substances such as minerals for microbial growth. A number of microbes can perform EEU, but only a subset of these organisms can perform phototrophic-EEU. This specialized metabolism harnesses the energy of light and electrons from solid-conductive minerals or their proxies (poised electrodes) to fix carbon dioxide. Accordingly, phototrophic-EEU represents a new metabolism to engineer for sustainable, carbon-neutral to carbon-sequestering bioproduction. To understand the environmental prevalence of phototrophic-EEU, and realize its full bioengineering potential, several fundamental knowledge gaps must be addressed. These include in-depth characterization of the electron input modules and their regulation; and the electron transfer pathways and the cellular electron sinks. Using multi-omic and transdisciplinary approaches, this project aims to fill these knowledge gaps to gain a systems-level understanding of phototrophic-EEU in the freshwater microbe, Rhodopseudomonas palustris and the marine microbe Rhodovulum sulfidophilum. The project will use synthetic biology, metabolic engineering, and material science to improve sustainable production of bioplastics and biofuels using phototrophic-EEU. Together, this project will expand our understanding of phototrophic-EEU, and explore the production of sustainable bioproducts using the phototrophic-EEU capable microbe, Rhodopseudomonas palustris. This project will also engage students from various educational levels in sustainability research.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.