Improving the performance and efficiency of heterotrophic carbon fixation through strain engineering and membrane-based CO2 delivery

大气中二氧化碳含量的升高是气候变化的重要原因。光合作用从空气中吸收二氧化碳并产生糖。有些微生物是光合作用的。其他微生物在将糖发酵成有机酸的过程中可以吸收二氧化碳。该项目的目的是提高非光合微生物对二氧化碳的吸收和利用。微生物将被改造得更有效率。将开发一种生物反应器，使二氧化碳能够有效和直接地输送到细胞中。通过研究、教育和推广活动，该项目将吸引学生进入STEM学科，培养他们对这些领域的兴趣，并激励他们继续在STEM领域获得更高的学位和职业。将评估解决与有效输送和异养固定二氧化碳相关的持续瓶颈的战略。大肠杆菌生产琥珀酸盐将成为模型系统。将设计用于发酵CO2固定的高性能生物催化剂。将增加多个协同的无机碳吸收系统。通过蛋白质工程和进化策略来提高磷酸烯醇丙酮酸羧激酶的催化活性。一系列采用无孔中空纤维膜的生物反应器将被设计、建造和数学建模，以实现高效、无气泡和按需输送二氧化碳。最终，这些努力可以支持二氧化碳的输送及其异养固定，比目前的技术水平更快，效率更高。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。

Elevated levels of carbon dioxide in the atmosphere contribute significantly to climate change. Photosynthesis pulls carbon dioxide out of the air and creates sugars. Some microbes are photosynthetic. Other microbes can take up carbon dioxide as they ferment sugars to organic acids. The objective of this project is to improve carbon dioxide uptake and use by non-photosynthetic microbes. Microbes will be engineered to be more efficient. A bioreactor will be developed to enable efficient and direct CO2 delivery to cells. Through research, education, and outreach activities, this project will attract students to STEM disciplines, cultivate their interest in these areas, and inspire them to continue towards advanced degrees and careers in STEM fields. Strategies to address persistent bottlenecks associated with efficient delivery and heterotrophic fixation of CO2 will be evaluated. Succinate production by Escherichia coli will be the model system. High-performance biocatalysts for fermentative CO2 fixation will be engineered. Multiple, synergistic inorganic carbon uptake systems will be added. Protein engineering and evolution strategies to enhance the catalytic activity of phosphoenolpyruvate carboxykinase will be implemented. A series of bioreactors incorporating non-porous hollow-fiber membranes for efficient, bubble-free, and on-demand CO2 delivery will be designed, constructed, and modeled mathematically. Ultimately, these efforts could support CO2 delivery and its heterotrophic fixation at faster rates and at higher efficiencies than the current state of the art.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.