Abstract:

In order to achieve carbon neutrality and green economy, people use biorefinery technology to transform and utilize CO₂. Microbial electrosynthesis (MES) is an emerging technology that converts CO₂ into chemicals by electrically driven biocatalysts. Currently, the low efficiency of microbial carbon sequestration, an incomplete understanding of electron transfer mechanisms, low synthesis rate, and poor applicability of reactor components have been the limiting factors for the large-scale application of MES. In this paper, the mechanisms of electron supply in the MES system, including through electrodes and electron donors such as H₂, formic acid, CO, and other molecules, are systematically reviewed based on how cathodic microorganisms obtain electrons. It is an effective method to improve electron transport efficiency by modifying conductive nanowires of electroactive microorganisms and optimizing the expression of microbially associated hydrogenase, formate dehydrogenase and CO dehydrogenase using synthetic biology techniques. Additionally, cathode modification aimed at improving electron transfer rates between microbes and electrodes, enhancing the biocompatibility, and providing more reducing power can facilitate the generation of value-added products. In addition to enhancing the electron transfer efficiency of the cathode, the construction of a reactor with high efficiency of gas-liquid-solid mass transfer and electron transfer, the reduction of anode potential for water electrolysis, and the regulation of microbial activity are also important strategies to enhance MES performance. In the future, it is necessary to further analyze the mechanism of microbial electron transport and strengthen the performance of MES by means of synthetic biological communities, and by designing a more efficient electrode interface that balances electron transfer rate, substrate mass transfer and biocompatibility. In terms of the scaling-up of reaction devices, electron transfer and gas mass transfer can be improved through the combination of various methods, and integrating product separation processes can promote the further development of the technology and provide new ideas for the realization of the "Carbon Peak and Carbon Neutrality" goal.

Key words: microbial electrosynthesis, CO₂ conversion, electron transfer mechanisms, chemicals

摘要：

为了实现碳中和绿色经济，人们利用生物炼制技术对二氧化碳（CO₂）进行转化利用。其中，微生物电合成（MES）是通过电能驱动生物催化剂将CO₂转化为化学品的新兴技术。目前MES仍存在微生物固碳效率低、电子传递机制未明确、产品合成速率低、反应器元件适用性差等问题，这成为其规模化应用的限制因素。本文基于阴极微生物获得电子的途径，系统地综述了电极、H₂、甲酸、CO以及其他电子供体在MES系统内的电子供给机制。通过合成生物学改造电活性微生物的导电纳米线、优化微生物相关氢化酶、甲酸脱氢酶和CO脱氢酶的表达是提高电子传递效率的有效方法。进一步通过阴极修饰，强化微生物-电极间电子传递速率、提高生物相容性，提供更多的还原力有利于高附加值产物的生成。除了增强阴极的电子传递效率，构建具有高效气液固传质和电子传递的反应器、降低阳极电解水电位和调控微生物活性等也被证明是提高MES性能的重要策略。未来需要进一步解析微生物电子传递机制，利用合成生物群落的方式强化MES的性能。并构建更加高效的电极界面，兼顾电子传递速率、底物传质和生物相容性。反应装置放大方面，可通过多种方式的结合来提升电子传递和气体传质，并将产物的分离也融合在一起， 推动该技术的进一步发展，为“双碳”目标的实现提供新思路。

关键词: 微生物电合成, CO2转化, 电子传递机制, 化学品