Microbial Electrosynthesis Systems Facilitating CO2 Valorization:Advances in Acetate Synthesis via the Reductive Acetyl-CoA Pathway

LIN Rujing; HU Tiantian; ZHANG Yue; XIE Li

doi:10.20078/j.eep.20250502

Abstract：The Microbial electrosynthesis system(MES)represents a significant interdisciplinary innovation that synergizes microbial reductive metabolism with electrochemical technology.By leveraging the metabolic capabilities of electroactive microorganisms and renewable electricity inputs,MES provides a sustainable platform for converting CO2 into value-added chemicals and mitigating greenhouse gas emissions.Among the various products derived from biological CO2 conversion,acetate has emerged as a key target due to its versatility as a chemical precursor and energy carrier.With applications in food preservation,biopolymer synthesis,and renewable fuel production,acetate holds substantial market value and economic potential,positioning MES as a transformative solution for carbon utilization.At the core of this process lies the reductive acetyl-CoA pathway,commonly known as the Wood-Ljungdahl pathway,a unique metabolic mechanism employed by acetogenic bacteria for efficient CO2 fixation and energy conservation.Unlike conventional CO2 fixation pathways,this pathway allows the direct reduction of CO2 into acetyl-CoA through a series of enzymatic reactions powered by electrons sourced from electrodes or hydrogen.This mechanism achieves high carbon reduction efficiency and offers thermodynamic stability under ambient conditions,making it a cornerstone for scalable CO2-to-acetate conversion.This review examines recent advancements in MES-driven acetate synthesis,with a focus on the optimization of the reductive acetyl-CoA pathway.Optimization strategies are categorized into three areas:(1)Enhancing electron transfer efficiency:The application of nanostructured catalysts has proven effective in accelerating electron transfer to microbial communities,thereby synergistically promoting both indirect and direct electron transfer pathways.(2)Regulating metabolic pathways:Enhancing in situ hydrogen generation and utilization,as well as supplementing with key intermediates such as CO and formate,can significantly improve the conversion of CO2 into value-added products.(3)Integrating CO2 capture and conversion:Coupling MES with advanced adsorbents or gas diffusion electrodes facilitates efficient CO2 mass transfer,addressing solubility limitations in aqueous systems.Finally,future research directions are proposed:(1)Catalyst design driven by machine learning:Integrating experimental data with neural networks could accelerate the identification of optimal electrode materials.(2)Synthetic biology for strain optimization:Applying gene-editing technologies to engineer microbial chassis can significantly enhance electron transfer capacity and improve the efficiency of target product synthesis.(3)System-level sustainability analysis:Life cycle assessments should guide reactor scaling to balance energy inputs with environmental benefits and ensure net-negative carbon emissions.By bridging fundamental insights with engineering innovations,this work provides a comprehensive framework to advance MES from lab-scale prototypes to industrial carbon refineries,ultimately contributing to a circular carbon economy.