Department of Physics and Astronomy, University of Southern California, 920 Bloom Walk, Seaver Science Center 215C, Los Angeles, CA 90089-0484, USA.
Phys Chem Chem Phys. 2012 Oct 28;14(40):13802-8. doi: 10.1039/c2cp41185g. Epub 2012 Jul 13.
Dissimilatory metal-reducing bacteria are microorganisms that gain energy by transferring respiratory electrons to extracellular solid-phase electron acceptors. In addition to its importance for physiology and natural environmental processes, this form of metabolism is being investigated for energy conversion and fuel production in bioelectrochemical systems, where microbes are used as biocatalysts at electrodes. One proposed strategy to accomplish this extracellular charge transfer involves forming a conductive pathway to electrodes by incorporating redox components on outer cell membranes and along extracellular appendages known as microbial nanowires within biofilms. To describe extracellular charge transfer in microbial redox chains, we employed a model based on incoherent hopping between sites in the chain and an interfacial treatment of electrochemical interactions with the surrounding electrodes. Based on this model, we calculated the current-voltage (I-V) characteristics and found the results to be in good agreement with I-V measurements across and along individual microbial nanowires produced by the bacterium Shewanella oneidensis MR-1. Based on our analysis, we propose that multistep hopping in redox chains constitutes a viable strategy for extracellular charge transfer in microbial biofilms.
异化金属还原菌是通过将呼吸电子转移到细胞外固相电子受体来获取能量的微生物。除了对生理学和自然环境过程的重要性外，这种代谢形式还在生物电化学系统中的能量转换和燃料生产中得到了研究，在生物电化学系统中，微生物被用作电极处的生物催化剂。一种实现这种细胞外电荷转移的拟议策略是通过在外细胞膜上和生物膜内称为微生物纳米线的细胞外附属物中加入氧化还原组件来形成与电极的导电途径。为了描述微生物氧化还原链中的细胞外电荷转移，我们采用了一种基于链中位点之间非相干跳跃的模型，并对与周围电极的电化学相互作用进行了界面处理。基于该模型，我们计算了电流-电压（I-V）特性，发现结果与通过单个人类纳米线产生的细菌 Shewanella oneidensis MR-1 进行的 I-V 测量非常吻合。基于我们的分析，我们提出氧化还原链中的多步跳跃是微生物生物膜中细胞外电荷转移的可行策略。
