This study investigated the molecular mechanism behind the highly efficient performance of nitrogen-doped carbon dots (NCDs)-assisted microbial electrosynthesis systems (MESs). The impact of NCDs (C:N precursor = 1:0.5–1:3) on acetogens was examined in the biocathode. The highest electrocatalytic performance was observed with NCDs1:1. The maximum acetate production rate of 1.9 ± 0.1 mM d−1 was achieved in NCDs1:1-modified MESs, which was 26.7–216.7 % higher than other MESs (0.6–1.5 mM d−1). With NCDs1:1 modified, the biocathode exhibited a 129.3–186.8 % increase in the abundance of Sporomusa, and 38.5–104.6 % increase in cytochrome expression (cydAB, cybH). Transcriptome confirmed that cytochromes played a crucial role in the extracellular electron uptake (EEU) of NCDs1:1-modified Sporomusa. NCDs1:1 enhanced EEU efficiency, thereby increasing the two H+-pumping steps and accelerating microbial CO2 fixation. These results provide valuable insights into increasing CO2 fixation by maximizing EEU efficiency in acetogens.

中文翻译：

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氮掺杂碳点通过有效的细胞外电子摄取产乙酸促进微生物电合成


本研究调查了氮掺杂碳点（NCD）辅助微生物电合成系统（MES）高效性能背后的分子机制。在生物阴极中检查了 NCD（C:N 前体 = 1:0.5–1:3）对产乙酸菌的影响。 NCDs1:1 观察到最高的电催化性能。 NCDs1:1 修饰的 MES 实现了 1.9 ± 0.1 mM d−1 的最大乙酸生产率，比其他 MES (0.6–1.5 mM d−1) 高 26.7–216.7%。经过 NCDs1:1 修饰后，生物阴极的 Sporomusa 丰度增加了 129.3–186.8%，细胞色素表达（cydAB、cybH）增加了 38.5–104.6%。转录组证实细胞色素在 NCDs1:1 修饰的孢子虫的细胞外电子摄取 (EEU) 中发挥着至关重要的作用。 NCDs1:1 提高了 EEU 效率，从而增加了两个 H+ 泵送步骤并加速了微生物 CO2 固定。这些结果为通过最大限度地提高产乙酸剂中的 EEU 效率来增加二氧化碳固定提供了宝贵的见解。