<br>硫还原地杆菌生物膜的双向细胞外电子传递途径：细胞外聚合物的分子洞察,Environmental Research

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硫还原地杆菌生物膜的双向细胞外电子传递途径：细胞外聚合物的分子洞察
Environmental Research ( IF 7.7 ) Pub Date : 2023-12-24 , DOI: 10.1016/j.envres.2023.118038
Guiqin Yang ₁ , Xue Xia ₁ , Weijie Nie ₁ , Baoli Qin ₁ , Tiqun Hou ₁ , Annian Lin ₁ , Sijie Yao ₁ , Li Zhuang ₁

Affiliation

生物电化学技术的基础是电活性细菌（EAB）利用电极进行双向细胞外电子转移（EET）的能力，即向外和向内EET。 EAB周围的胞外聚合物（EPS）是EET的必要介质，但对电极表面生物膜EPS的生化和分子分析却很缺乏。本研究构建了执行双向 EET 的生物膜，利用电化学、光谱指纹和蛋白质组学技术通过 EPS 表征来探索双向 EET 机制。结果表明，相对于外向 EET，内向 EET 需要具有较低形式电势的细胞外氧化还原蛋白。与从阳极生物膜中提取的EPS（A-EPS）相比，从阴极生物膜中提取的EPS（C-EPS）表现出较低的氧化还原活性，这主要是由于蛋白质/多糖比和蛋白质的α-螺旋含量降低。此外，与 A-EPS 相比，C-EPS 中检测到的细胞色素较少，酪氨酸和色氨酸蛋白样物质较多，表明细胞色素的作用减弱，而其他氧化还原蛋白在内向 EET 中可能发挥作用。蛋白质组学分析鉴定出 EPS 中多种氧化还原蛋白，包括细胞色素、含铁硫簇的蛋白、黄素蛋白和氢化酶，它们可能作为双向 EET 的细胞外氧化还原网络。在 A-EPS 和 C-EPS 中受到显着刺激的那些氧化还原蛋白可能对于向外和向内 EET 至关重要，值得进一步研究。这项工作揭示了生物膜双向 EET 的机制，对提高生物电化学技术的性能具有重要意义。

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Bidirectional extracellular electron transfer pathways of Geobacter sulfurreducens biofilms: Molecular insights into extracellular polymeric substances

The basis for bioelectrochemical technology is the capability of electroactive bacteria (EAB) to perform bidirectional extracellular electron transfer (EET) with electrodes, i.e. outward- and inward-EET. Extracellular polymeric substances (EPS) surrounding EAB are the necessary media for EET, but the biochemical and molecular analysis of EPS of biofilms on electrode surface is largely lacked. This study constructed biofilms performing bidirectional EET to explore the bidirectional EET mechanisms through EPS characterization using electrochemical, spectroscopic fingerprinting and proteomic techniques. Results showed that the inward-EET required extracellular redox proteins with lower formal potentials relative to outward-EET. Comparing to the EPS extracted from anodic biofilm (A-EPS), the EPS extracted from cathodic biofilm (C-EPS) exhibited a lower redox activity, mainly due to a decrease of protein/polysaccharide ratio and α-helix content of proteins. Furthermore, less cytochromes and more tyrosine- and tryptophan-protein like substances were detected in C-EPS than in A-EPS, indicating a diminished role of cytochromes and a possible role of other redox proteins in inward-EET. Proteomic analysis identified a variety of redox proteins including cytochrome, iron-sulfur clusters-containing protein, flavoprotein and hydrogenase in EPS, which might serve as an extracellular redox network for bidirectional EET. Those redox proteins that were significantly stimulated in A-EPS and C-EPS might be essential for outward- and inward-EET and warranted further research. This work sheds light on the mechanism of bidirectional EET of biofilms and has implications in improving the performance of bioelectrochemical technology.

更新日期：2023-12-24

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