Self-assembled FeS-Clostridium ljungdahlii biohybrid boost chemicals production in microbial electrosynthesis

The low extracellular electron transfer rate ofClostridium ljungdahliilimits its capacity to acquire reducing power from the electrode for CO₂ reduction and chemical synthesis. Herein, we employ a biologically self-assembled FeS construct to accelerate electron transfer forC. ljungdahlii, which enhances CO₂-to-chemical conversion in microbial electrosynthesis (MES). The synthesized FeS nanoparticles werelocalized tothe cell surface and intracellular space ofC. ljungdahlii, thereby establishing a contiguous, bio-derived conductive network across the cellular boundary. The enhanced electron uptake capability drove a dramatic improvement in CO₂ reduction, increasing the yields of acetate, butyrate, and 2,3-butanediol by up to 10.5‑fold, 2.63‑fold, and 4.23‑fold, respectively. The biohybrid system achieved an impressive acetate yield of 1.01 g L^-1 d^-1 in long-term operation. The enhancement in chemicals synthesis within the Clostridium ljungdahlii-FeS biohybrid is attributed to the increased NADH/NAD⁺ ratio and electron transfer rate as well as the up-regulation of genes involved in carbon fixation, electron transfer, and energy conversion. This biohybrid structure dramatically elevated the direct electron transfer ratio of C. ljungdahlii from 18% to 78%, thereby reducing reliance on dissolved H₂. This work provides an efficient, light-independent strategy for augmenting CO₂-to-chemical conversion via enhanced direct electron transfer in MES.