Abstract:

Carbon dioxide (CO₂) is the main greenhouse gas, but it also represents an abundant, cost-effective, safe, and easily accessible carbon resource. Driven by the national goals to achieve "carbon peaking and carbon neutrality", there has been an increasing interest in recent years in effective reduction of CO₂ emission and utilization of this one-carbon resource, thereby accelerating the development of carbon capture, utilization, and storage (CCUS) technologies. Biological conversion plays a major role in CCUS. This approach enables the transformation of CO₂ into desired products through either direct biological catalysis or in combination with chemical catalysis (using CO₂-derived organic compounds such as methanol, formic acid, and acetic acid). Thus, biological CO₂ fixation and conversion represents a promising solution for both utilization of greenhouse gas or industrial waste gases and sustainable production of bulk chemicals and fuels. However, the current state of biotransformation technology for CCUS is still in its infancy, leaving ample room for improvement in the efficiency, yield, and cost-effectiveness. In this review, we briefly summarize recent advances in biological utilization of CO₂, highlight the characteristics and limitations of the existing technologies, and also propose future research directions. Our aim is to provide a valuable reference to researchers in this field. Overall, industrial application of CO₂ bioconversion remains in its nascent phase. Although industrial-scale ethanol production through syngas (CO₂/CO) fermentation by chemoautotrophic bacteria has made significant strides, there is still a need for further improvement in the conversion efficiency of CO₂. In addition, gas fermentation should consider more value-added products beyond ethanol to enhance the economic viability of this technology. Other CO₂ bioutilization technologies, such as the coupling of chemical and biological conversion and in vitro enzymatic catalysis, have yet to bridge the gap to large-scale applications. Therefore, further optimization of these technical systems and reduction of production cost are essential to meet the needs of industrial applications.

Key words: carbon dioxide, organic low carbon, biological utilization, in vitro enzymatic catalysis, value-added products

摘要：

二氧化碳（CO₂）是主要的温室气体，但同时也是一种储量巨大、廉价、安全且易得的可再生资源。在我国“碳达峰、碳中和”战略目标的驱动下，如何有效减少CO₂排放并转而利用这一重要碳资源已成为当前的研究热点与重点，这同时也加快了CO₂捕集、利用与封存（carbon capture， utilization and storage， CCUS）技术的发展和创新。生物转化是实现CO₂利用的主要路径之一，既能够直接催化、转化CO₂合成目标产物，也可以与化学催化路径相耦合实现对CO₂来源的有机低碳资源（如甲醇、甲酸、乙酸）的有效转化及定向合成，因此有望在国家“双碳”目标的实现中发挥重要作用。本文对近年来CO₂生物转化的研究进展进行了梳理和总结，指出了现有技术路线的特点和不足，并对今后的研究重点和方向提出了建议。总体而言，CO₂生物利用技术目前尚处于起步阶段。基于化能自养细菌的合成气（CO₂/CO）发酵生产乙醇虽已实现工业化，但仍需要进一步优化和提高CO₂的转化利用效率，并获得除乙醇外更多的高值产品，从而提升整个技术路线的经济性。而其他的CO₂生物转化路径，无论是化学-生物发酵耦合还是体外酶催化，目前离大规模应用还有较大距离，需要进一步优化技术体系和降低成本来满足工业化需求。

关键词: 二氧化碳, 有机低碳, 生物利用, 体外酶催化, 高附加值产品