Title: Direct CO₂ transformation to malate via bioelectrosynthesis upon engineered Shewanella oneidensis

Authors: Yixin Li,# Dong Xia,*# Yinuo Xie, Rong Dong, Mingfeng Cao,* Qingbiao Li, Yuanpeng Wang*

Abstract: Microbial electrosynthesis (MES) offers a sustain-able and low-carbon approach for CO₂ valorization, withShewanella oneidensis (S. oneidensis) MR-1 identified as an idealmicrobe for MES. However, no prior research has demonstratedthat S. oneidensis MR-1 can directly metabolize CO₂ intomulticarbon (C₂₊) products due to its inability to perform theintracellular formate assimilation pathway. Here, we provide initialproof-of-concept evidence of direct bioelectrochemical CO₂reduction to the C₄ product of malate. Specifically, the trans-formation of CO₂ to malate attains a notable productionconcentration of 1.18 mmol·L−1, marking the first instance ofdirect C₄ compound bioelectrosynthesis. Such remarkable CO₂-to-C₄ conversion performances are attributed to the successful implementation of dual-plasmid systems in S. oneidensis MR-1, whichfacilitate the overexpression of the reductive glycine pathway (Plasmid I) for assimilating CO_2-derived formate and the alternativemalate biosynthetic pathway (Plasmid II) to channel metabolic intermediates toward the biosynthesis of malate. Advancing CO₂ valorization toward carbon-negative C₂₊ bioproducts, our sophisticated dual-plasmid systems engineered in microbes can be furtherrefined for scalable CO₂ bioelectrolysis with the objective of facilitating industrial applications.

Full-Link: https://doi.org/10.1021/jacs.5c01494