Lee Hyeonsik, Bae Jiyun, Jin Sangrak, Kang Seulgi, Cho Byung-Kwan
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea.
KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, South Korea.
Front Microbiol. 2022 May 9;13:865168. doi: 10.3389/fmicb.2022.865168. eCollection 2022.
C1 gases, including carbon dioxide (CO) and carbon monoxide (CO), are major contributors to climate crisis. Numerous studies have been conducted to fix and recycle C1 gases in order to solve this problem. Among them, the use of microorganisms as biocatalysts to convert C1 gases to value-added chemicals is a promising solution. Acetogenic bacteria (acetogens) have received attention as high-potential biocatalysts owing to their conserved Wood-Ljungdahl (WL) pathway, which fixes not only CO but also CO. Although some metabolites have been produced C1 gas fermentation on an industrial scale, the conversion of C1 gases to produce various biochemicals by engineering acetogens has been limited. The energy limitation of acetogens is one of the challenges to overcome, as their metabolism operates at a thermodynamic limit, and the low solubility of gaseous substrates results in a limited supply of cellular energy. This review provides strategies for developing efficient platform strains for C1 gas conversion, focusing on engineering the WL pathway. Supplying liquid C1 substrates, which can be obtained from CO, or electricity is introduced as a strategy to overcome the energy limitation. Future prospective approaches on engineering acetogens based on systems and synthetic biology approaches are also discussed.
C1气体，包括二氧化碳（CO₂）和一氧化碳（CO），是气候危机的主要促成因素。为了解决这个问题，人们已经进行了大量研究来固定和循环利用C1气体。其中，利用微生物作为生物催化剂将C1气体转化为高附加值化学品是一个很有前景的解决方案。产乙酸细菌（产乙酸菌）因其保守的伍德-Ljungdahl（WL）途径而受到关注，被视为具有高潜力的生物催化剂，该途径不仅能固定CO₂，还能固定CO。尽管通过C1气体发酵已经在工业规模上生产了一些代谢产物，但通过工程改造产乙酸菌将C1气体转化为各种生物化学品的过程仍然有限。产乙酸菌的能量限制是需要克服的挑战之一，因为它们的代谢在热力学极限下运行，气态底物的低溶解度导致细胞能量供应有限。本综述提供了开发用于C1气体转化的高效平台菌株的策略，重点是对WL途径进行工程改造。引入可从CO₂获得的液态C1底物或电力作为克服能量限制的策略。还讨论了基于系统和合成生物学方法对产乙酸菌进行工程改造的未来前瞻性方法。
