关键词: 第三代生物炼制, 二氧化碳, 生物同化途径, 可再生能源, 合成生物学, 生物制造

Abstract:

CO₂ captures worldwide attention these days because of the urgent need to counteract its ever increasing in the atmosphere and its impact on climate change, with the ultimate goal of carbon neutrality. Recently, large efforts have been made in CO₂ capture and utilization, primarily using physical or chemical means. Biotechnological CO₂ capture and utilization has been mainly studied using microalgae, but turned out to be economically less competitive. Large-scale biotechnological capture and utilization of CO₂ thus urgently needs new concepts and technologies. The teams of Tan Tianwei and Jens Nielsen (Liu et al, 2020) recently reviewed the advances and challenges in biological CO₂ fixation in the context of third-generation (3G) biorefineries. The review gives an excellent survey and valuable discussions on sources of CO₂, the natural and synthetic CO₂ fixation pathways, use of regenerative energy, and 3G-based products. Perspectives of 3G biorefineries are also presented. It is clear that each CO₂ fixation pathway has its benefits and drawbacks and the choice depends on the microbial host, the target product(s), and the preferred process and cultivation conditions. In addition to the technical aspects, the authors also emphasized the necessity of further increasing social, political and economic incentives for continued financial support of research and small companies. This commentary briefly introduces the major points of the review of Liu et al. and discusses further aspects on the move from basic research to industrial application of CO₂ based biomanufacturing. In particular, we emphasize the following aspects: (1) More fundamental and quantitative studies on the underlying mechanisms of carbon binding and transformation to significantly increase the efficiency of key enzymes and metabolic modules of the different fixation pathways; (2) The interactions of CO₂ fixation pathway with metabolic network and their regulation deserve more systems level and quantitative study; (3) Integration of physical, chemical and electrochemical CO₂ capture and transformation methods with biological processes in the sense of biorefineries, also by considering the downstream processing of product recovery; (4) From the perspective of industrial application, autotrophic synthesis-based biomanufaturing has several major technological bottlenecks and economic constraints, mixotrophic biosynthesis (using CO₂ and mixed carbon sources) seems a practical solution and deserves more attention; (5) Finally, most of the CO₂ fixation pathways and their products are still at the proof of concept stage, engineering breakthroughs are urgently needed for moving from “0 to 1” to“1 to 100”and thus to really contribute to carbon neutrality.

Key words: third-generation (3G) biorefineries, carbon dioxide, fixation pathway, regenerative energy, synthetic biology, biomanufacturing