SusChEM: Biological Auto-Enhancement of CO2 Absorption for Improved Cyanobacterial Growth and Biofuel Production

光养微生物利用阳光制造化学品作为营养，具有作为“微生物化学工厂”的潜力，可以利用阳光和水作为能源，直接从大气中的二氧化碳中制造可持续的燃料和化学品。这种方法的一个技术挑战是含有微生物的水溶液对CO2的吸收较差。在转化CO2的其它工业方法中，使用链烷醇胺溶剂如单乙醇胺（MEA）可用于提高CO2水溶液溶解度，进而提高其从气流中吸收的速率和效率。该项目旨在设计一种模式蓝细菌生物，通过光合作用直接产生MEA。 在所产生的MEA存在下，将显著提高CO2吸收到生物体培养基中的速率和效率，因此，细胞生长和生物燃料生产的速率也将显著提高。此外，还将包括研究、教育和外联的多方面方法。该项目将作为几个高中和本科生研究项目的基础，涉及富尔顿本科生研究计划（FURI），生命科学本科生研究（SOLUR）的学校，以及科学和工程经验（SCENE）计划招收妇女和代表性不足的少数民族学生。 一种新的代谢途径将被改造，使MEA生物合成从内源性前体集胞藻属PCC 6803。 这将通过去调节天然前体生物合成途径，然后引入和优化异源途径步骤的表达来实现。在水性培养物内，CO2将与产生的MEA反应，然后通过一系列后续反应，最终将呈现为碳酸氢盐。 碳酸氢盐的细胞同化将促进产生的MEA的进一步再生，从而使其再次与额外的CO2分子反应。 为了促进MEA的生物再生，该项目将包括提高碳酸氢盐吸收的战略。最后，增强的CO2吸收将支持微生物的更高生长速率，增加的生长将支持MEA生产的更高速率，更大的MEA可用性将支持进一步改善的CO2吸收，最终导致自催化效应。这些策略将在野生型集胞藻以及先前工程化的月桂酸生产菌株中进行研究，从而使MEA生物合成对这种重要的脂肪酸生物燃料前体的生产的影响得以探索。

Phototrophic microorganisms, which use sunlight to make chemicals for their nutrition, possess potential as "microbial chemical factories" to make sustainable fuels and chemicals directly from atmospheric CO2, using sunlight and water for energy. One technical challenge to this approach is poor CO2 absorption into the aqueous solution containing the microbes. In other industrial processes that convert CO2, use of alkanolamine solvents such as monoethanolamine (MEA), can be used to enhance aqueous CO2 solubility and, in turn, the rate and efficiency of its absorption from gas streams. This project seeks to engineer a model cyanobacterium organism to produce MEA directly via photosynthesis. In the presence of produced MEA, the rate and efficiency of CO2 absorption into the organism's culture medium will be significantly enhanced and, as a result, so too will be rates of cell growth and biofuel production. In addition, a multi-faceted approach to research, education, and outreach will also be included. This project will serve as the basis for several high school and undergraduate student research projects involving the Fulton Undergraduate Research Initiative (FURI), School of Life Sciences Undergraduate Research (SOLUR), and the SCience and ENgineering Experience (SCENE) programs to recruit women and under-represented minority students. A novel metabolic pathway will be engineered to enable MEA biosynthesis from endogenous precursors in Synechocystis sp. PCC 6803. This will be achieved by deregulating a native precursor biosynthesis pathway, followed by the introduction and optimized expression of the heterologous pathway steps. Within the aqueous culture, CO2 will react with produced MEA and then, through a series of subsequent reactions, will ultimately be rendered as bicarbonate. Cellular assimilation of bicarbonate will promote further regeneration of produced MEA, thereby returning it to react again with additional CO2 molecules. To facilitate the biological regeneration of MEA, the project will include strategies to enhance bicarbonate uptake. In the end, enhanced CO2 absorption will support higher growth rates of the microbes, increased growth will support higher rates of MEA production, greater MEA availability will support further improved CO2 absorption, ultimately resulting in an auto-catalytic effect. These strategies will be investigated in both wild-type Synechocystis as well as a previously-engineered laurate-producing strain, thereby allowing the effects of MEA biosynthesis on the production of this important fatty acid biofuel precursor to be explored.