摘要
随着化石资源的过度开发和利用,由CO_(2)过度排放引起的全球变暖已经引起全世界的高度关注,亟待找到可持续的替代解决方案.利用微生物作为细胞工厂,对天然碳代谢途径进行改造以实现更大程度的碳保留及利用天然碳固定途径和人工固碳途径,将碳源转化为可利用碳物质,是减少碳排放、缓解温室效应的有效途径.本文以微生物系统在其代谢过程中优化碳保存及碳固定的能力为主要标准,主要总结了近年来人工碳保留途径和人工固碳途径设计合成方面取得的进展,并进行了比较分析,讨论了以微生物作为细胞工厂实现绿色低碳可持续生产的价值.随着合成生物学的不断发展,越来越多的二氧化碳固定机制将被挖掘和开发,用于重构微生物代谢,实现高效的生物制造,开启工业脱碳的正循环.
Since the Industrial Revolution,carbon dioxide(CO_(2))emissions have increased significantly,and global warming caused by excessive CO_(2) emissions has attracted great attention worldwide.With the development of biotechnology,the modification of natural carbon metabolic pathways using microorganisms as cell factories to achieve bettter carbon conservation,and the utilization of natural carbon fixation pathways and artificial carbon sequestration pathways to convert renewable carbon sources into alternative energy sources is the promising green energy solutions.In this review,with the ability of microbial systems optimizing carbon conservation and carbon fixation during their metabolic processes as the main criteria,we summarize the progress made in recent years in the design and synthesis of artificial carbon conservation pathways and artificial carbon fixation pathways,and conduct a comparative analysis to discuss the value of using microorganisms as cell factories for low-carbon sustainable production.The conversion of carbon sources to chemicals using acetyl-CoA as precursor is achieved mainly through the EMP pathway in the natural carbon metabolic pathway,and the carbon loss of metabolic pathway is caused by the decarboxylation process of pyruvate conversion to acetyl-CoA.In order to improve efficiency of carbon fixation,the researchers used synthetic biology to redesign and construct the carbon metabolic process of heterotrophic microorganisms,which can bypass the pyruvate decarboxylation process and achieve maximum carbon conservation during metabolism,thus improving the effective use of carbon sources.Herein,the non-oxidative artificial glycolytic pathway and its optimized construction of EP-Bifido pathway are discussed in detail.In addition,the introduction of effective CO_(2) fixation pathways by optimizing natural carbon fixation pathways or designing artificial carbon fixation cycle pathways is also an important direction to construct artificial carbon saving pathways.There are two main ways to introduce one-carbon compounds into the metabolic pathway,one is through the direct utilization of one-carbon compounds such as formate and methanol,and there have been many excellent reviews on this type of carbon fixation pathway.Herein,the carbon fixation pathway summarized in this paper is to realize the utilization of CO_(2) by introducing CO_(2) into the metabolic pathway.The artificial carbon fixation pathway has the advantages of short pathway and high efficiency of carbon fixation enzymes,although some carbon fixation pathways cannot be realized in vivo,its carbon fixation efficiency is often better than the natural carbon fixation pathway.In the process of microbial fermentation,the production and release of CO_(2) are often accompanied by the production of NAD(P)H and ATP,and the process of CO_(2) fixation during carbon fixation is accompanied by the consumption of NAD(P)H.In the process of chemical production by heterotrophic microorganisms,excess reducing power is theoretically required to achieve a net gain in CO_(2) fixation.The carbon in CO_(2) is in the highest valence state+4,it’s the most completely oxidized form of carbon-based compounds.The conversion of CO_(2) to the reduced product(carbon with an average valence of–2)requires NAD(P)H to provide electrons for the process.The main forms of reducing power in the carbon fixation pathway are NAD(P)H and the reduced state Fd.By enhancing some pathways such as the pentosephosphate pathway or the introduction of exogenous energy supply systems,the deficiency of NAD(P)H,can be compensated,thus benefiting the production of target chemicals.With the development of synthetic biology,more and more CO_(2) mechanisms of fixation will be explored and developed to reconfigure microbial metabolism for efficient biomanufacturing and start a positive cycle of industrial decarbonization.
作者
高华潇
王倩
祁庆生
Huaxiao Gao;Qian Wang;Qingsheng Qi(State Key Laboratory of Microbial Technology,National Glycoengineeing Research Center,Shandong University,Qingdao 266237,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2023年第19期2446-2456,共11页
Chinese Science Bulletin
基金
国家自然科学基金(32270089)
国家重点研发计划(SQ2019YFA090038)资助
关键词
碳保存
人工固碳
合成生物学
二氧化碳
生物基产品
carbon conservation
artificial carbon fixation
synthetic biology
carbon dioxide
bio-based products
作者简介
联系人:王倩,E-mail:qiqi20011983@sdu.edu.cn;联系人:祁庆生,E-mail:qiqingsheng@sdu.edu.cn
