Two Modes of Riboflavin-Mediated Extracellular Electron Transfer in Geobacter uraniireducens
Two Modes of Riboflavin-Mediated Extracellular Electron Transfer in Geobacter uraniireducens
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铀还原地杆菌中核黄素介导的细胞外电子转移的两种模式
DOI：
10.3389/fmicb.2018.02886
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发表时间：
2018-11-27
影响因子：
5.2
通讯作者：
Zhou, Shungui
中科院分区：
文献类型：
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作者：
Huang, Lingyan;Tang, Jiahuan;Zhou, Shungui
厌氧菌通过细胞外电子转移（EET）呼吸细胞外电子受体。人们普遍认为黄素可以作为电子穿梭器来促进这一过程。黄素合成基因在地杆菌中广泛分布。然而，黄素在地杆菌EET中的作用尚不清楚。在这里，我们证明了G. uraniireducens可以分泌丰富的核黄素（高达270 nM）来促进EET。当电极作为电子受体时，阳极氧化电流在阳极电解质替换后的快速恢复以及用差分脉冲伏安法表征的铀还原生物膜的电化学行为表明，自分泌核黄素通过作为细胞色素的结合氧化还原辅助因子促进了EET。相反，当Fe（III）氧化物为电子受体时，游离核黄素作为电子穿梭体介导Fe（III）氧化物的还原。结果表明黄素在EET中的灵活性，表明电子受体的性质可以影响细胞外黄素的结合方式，并拓宽了对Geobacter物种EET的认识。
Anaerobes respire extracellular electron acceptors by extracellular electron transfer (EET). It is widely recognized that flavins can act as electron shuttles to facilitate this process. Flavin synthesis genes are widely distributed in Geobacter species. However, the functions of flavins in the EET of Geobacter species are unclear. Here, we demonstrate that G. uraniireducens can secrete abundant riboflavin (up to 270 nM) to facilitate EET. When an electrode was used as the electron acceptor, the quick recovery of anodizing current after anolyte replacement and the electrochemical behavior of the G. uraniireducens biofilm characterized by differential pulse voltammetry suggest that the self-secreted riboflavin promoted EET by serving as bound redox cofactors for cytochromes. On the contrary, when Fe(III) oxide was the electron acceptor, free riboflavin acted as electron shuttle to mediate the reduction of Fe(III) oxide. The results demonstrate the flexibility of flavins in EET, suggesting that the properties of electron acceptors can affect the binding mode of extracellular flavins, and broaden the knowledge of the EET of Geobacter species.