Biofilm matrix and artificial mediator for efficient electron transport in CO2 microbial electrosynthesis
Biofilm matrix and artificial mediator for efficient electron transport in CO2 microbial electrosynthesis
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DOI：
10.1016/j.cej.2021.131885
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发表时间：
2022
影响因子：
15.1
通讯作者：
Y. Song;A. Mohamed;Changman Kim;Min‐Soo Kim;Shuwei Li;E. Sundstrom;H. Beyenal;J. R. Kim
中科院分区：
文献类型：
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作者：
Y. Song;A. Mohamed;Changman Kim;Min‐Soo Kim;Shuwei Li;E. Sundstrom;H. Beyenal;J. R. Kim
微生物电合成（MES）已经被强调为利用电作为还原力将无机气态碳（例如CO2）转化为增值化学品的手段。基于电极的电子转移通过生物膜基质或经由电子穿梭分子将呼吸电子递送到活细胞生物催化剂。人工介质如中性红（NR）和2-羟基-1，4-萘醌（HNQ）的加入显著增加了乙酸的合成，表明这些介质改善了悬浮细胞与电极之间的电子传递能力。定期更换介质还通过调整反应器中的介质利用物种来改善MES。没有介体的MES最初以合理的速率（5.1 ± 0.2 mmol/l/天）产生乙酸盐，但在后期该速率变得可忽略不计。相比之下，随着培养基更换的进行，使用NR或HNQ的MES显示出更高的乙酸盐产生速率（分别为4.6 ± 0.4和7.4 ± 0.4 mmol/l/天）。共聚焦激光扫描显微镜和3D成像显示，生物膜基质由活细胞和死细胞组成，而有和没有介体的MES中的组成不同。通过下一代测序（NGS）进行的微生物群落分析表明，在96天的运行期间，产乙酸乙酸杆菌（悬浮液中）和孢子菌（悬浮液和生物膜中）占优势。在MES条件下，生物膜和浮游生物群落动态地相互作用。该结果提供了MES中生物膜和增殖细胞的真实模型。悬浮细胞通过电子穿梭与生物膜形成电极的相互作用可以提高体积乙酸产量并稳定MES性能。
Microbial electrosynthesis (MES) has been highlighted as a means to valorize inorganic gaseous carbon, such as CO2, into value-added chemicals using electricity as the reducing power. Electrode-based electron transfer delivers respiratory electrons to a live-cell biocatalyst through a biofilm matrix or via electron shuttle molecules. The addition of artificial mediators, such as neutral red (NR) and 2-hydroxy-1,4-naphthoquinone (HNQ), increased acetate synthesis significantly, suggesting that these mediators improve the electron transport capability between the suspended cells and electrode. Regular media replacement also improves MES by adapting mediator-utilizing species in the reactor. MES without a mediator initially produced acetate at a reasonable rate (5.1 ± 0.2 mmol/l/day), but the rate became negligible in the later stage. In contrast, MES with NR or HNQ showed a higher acetate production rate (4.6 ± 0.4 vs. 7.4 ± 0.4 mmol/l/day, respectively) as the media replacement progressed. Confocal laser scanning microscopy and 3D imaging showed that the biofilm matrix consisted of live and dead cells, while the composition was different in the MES with and without a mediator. Microbial community analysis by next-generation sequencing (NGS) showed that acetogenicAcetobacterium(in suspension) andSporomusa(in both suspension and biofilm) were dominant during the 96 days of operation. The biofilm and planktonic community interacted dynamically under MES conditions. This result provides a realistic model of biofilms and planktonic cells in the MES. The interaction of the suspended cells with the biofilm-forming electrode via electron shuttles could improve volumetric acetate production and stabilize the MES performance.