Microbial electrosynthesis (MES) is a promising strategy for the conversion of CO₂ to useful chemicals. Nevertheless, the characteristics of electrode-associated cells in MES and their metabolic pathway regulation in CO₂ fixation have not been elucidated. This study examined the electrode-driven polyhydroxybutyrate (PHB) production from CO₂ in Rhodobacter sphaeroides. The electron uptake and regulation of the metabolic pathways differed in electrode-associated and suspended R. sphaeroides. The electrode-associated cells produced PHB at concentrations up to 23.50 ± 2.8% of the dry cell weight (DCW), whereas the suspended cells grew faster but with a lower cellular PHB content. Gene expression analyses showed that phaA expression was upregulated in electrode-associated R. sphaeroides, whereas phaB expression was downregulated in suspended cells. The electrode-associated cells expressed unconventional CO₂ fixation enzymes, such as isocitrate dehydrogenase and formate dehydrogenase, with more PHB synthesis. These results show that CO₂ can be upcycled to polymeric substances and provide novel insights into the genetic regulation of electrode-associated cells in MES.

_{微生物电合成 (MES) 是一种将 CO 2}转化为有用化学品的有前途的策略。然而，MES中电极相关细胞的特征及其在CO ₂固定中的代谢途径调控尚未阐明。本研究检测了球形红细菌中电极驱动的 CO ₂聚羟基丁酸酯 (PHB) 生产。电子摄取和代谢途径的调节在电极相关和悬浮的R. sphaeroides中不同. 电极相关细胞产生的 PHB 浓度高达干细胞重量 (DCW) 的 23.50 ± 2.8%，而悬浮细胞生长更快但细胞 PHB 含量较低。基因表达分析表明，phaA表达在电极相关的球形红球菌中上调，而phaB表达在悬浮细胞中下调。电极相关细胞表达非常规CO ₂固定酶，如异柠檬酸脱氢酶和甲酸脱氢酶，具有更多的PHB合成。这些结果表明，CO ₂可以升级循环为聚合物质，并为 MES 中电极相关细胞的遗传调控提供了新的见解。