SBIR Phase I: Novel Photosynthetic Biocatalysts for Synthesis of Malic Acid

这个小企业创新研究第一阶段项目旨在设计新型生物催化剂，用于从二氧化碳中经济高效地生产苹果酸。苹果酸是所有生物能量代谢的关键中间体。此外，两个羧基和一个羟基的存在使其成为生产各种化学品和化学中间体的重要组成部分。由于获得关键生物合成酶所需底物的固有限制，工程化异养生物催化剂生产苹果酸的尝试取得了有限的成功。我们已经开发出一种创新的策略，将这种关键酶共同定位在光合微生物中天然存在的羧基体内。核酮糖-1，5-二磷酸羧化酶/加氧酶利用羧化体克服其对CO2（共底物）的动力学缺陷。工程代谢途径将允许羧基体内天然产生的3-磷酸甘油酸转化为苹果酸。SBIR第一阶段研究项目的预期结果是建立一种开创性的、具有成本效益的技术，该技术将利用太阳能将二氧化碳转化为苹果酸。拟议研究的更广泛/商业成果将提供多种好处和应用：1）开发一种有效的生物催化剂，可以显着降低苹果酸的生产成本。更低的生产成本和多官能团的存在将打开新的市场机会。2)从可再生原料生产对映体纯的L-苹果酸，相对于通过化学方法生产的外消旋混合物，它是食品和药物应用的优选添加剂。3)这是一个减少现有生物燃料行业碳足迹的有吸引力的直接机会。4)有机会将其他利用CO2的酶靶向细胞内的这一位置，并更有效地利用CO2制造其他重要的生物分子，从而开辟新的商业可能性。5)最后，它将开辟机会，更有效地将光收集与碳固定联系起来，因为制造苹果酸的酶具有比RuBisCO高得多的周转能力。所提出的工艺技术的成功将有助于美国的经济和能源安全，减少对化石燃料的依赖和温室气体排放，并在化学工业中使用二氧化碳而不是排放。

This Small Business Innovation Research Phase I project aims to engineer novel biocatalysts for cost-effective production of malic acid from CO2. Malic acid is a key intermediate in energy metabolism of all living species. Additionally, presence of two carboxyl and one hydroxyl groups makes it an important building block for production of diverse chemicals and chemical intermediates. Attempts to engineer heterotrophic biocatalysts for production of malic acid have had limited success due to the inherent limitations of accessing the substrate required for the key biosynthetic enzyme. We have developed an innovative strategy to co-localize this key enzyme within carboxysomes naturally found in photosynthetic microorganisms. Carboxysomes are leveraged by ribulose-1,5-bisphosphate carboxylase/oxygenase to overcome their kinetic deficiency for CO2, a cosubstrate. The engineered metabolic pathway will allow conversion of 3- phosphoglycerate naturally produced inside carboxysome to malic acid. The anticipated result of this SBIR Phase 1 research project is establishment of a groundbreaking and cost-effective technology that will convert CO2 into malic acid using energy derive from sunlight. The Broader/Commercial outcome of the proposed research will be to offer multiple benefits and applications: 1) Development of an efficient biocatalyst that could significantly reduce the production cost of malic acid. Lower production cost and presence of multiple functional groups will open new market opportunities. 2) Production of enantiomerically pure L-malic acid from renewable feedstock, a preferred additive for food and pharmaceutical applications over the racemic mixtures produced by the chemical method. 3) An attractive and immediate opportunity to reduce carbon footprint of the existing biofuel industries. 4) Opportunity to target other CO2 utilizing enzymes to this locale within cells and to use CO2 more efficiently in making other important biomolecules thus opening new commercial possibilities. 5) Finally, it will open up the opportunity to link light harvesting more effectively to carbon fixation since enzymes that make malic acid have substantially higher turnover capability than RuBisCO. Success of the proposed process technology will contribute to the economic and energy security of the U.S. by reducing the dependence on fossil fuels and emission of greenhouse gas emission, and use of CO2 in the chemical industry instead of being an emitter.