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.