†State Key Laboratory of Clean Energy Utilization, Department of Energy Engineering, Zhejiang University, Hangzhou 310027, P.R. China.
‡Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, China Academy of Sciences, Beijing, China.
Environ Sci Technol. 2015 Apr 21;49(8):5227-35. doi: 10.1021/acs.est.5b00175. Epub 2015 Apr 7.
Sustained current generation by anodic biofilms is a key element for the longevity and success of bioelectrochemical systems. Over time, however, inactive or dead cells can accumulate within the anode biofilm, which can be particularly detrimental to current generation. Mixed and pure culture (Geobacter anodireducens) biofilms were examined here relative to changes in electrochemical properties over time. An analysis of the three-dimensional metabolic structure of the biofilms over time showed that both types of biofilms developed a live outer-layer that covered a dead inner-core. This two-layer structure appeared to be mostly a result of relatively low anodic current densities compared to other studies. During biofilm development, the live layer reached a constant thickness, whereas dead cells continued to accumulate near the electrode surface. This result indicated that only the live outer-layer of biofilm was responsible for current generation and suggested that the dead inner-layer continued to function as an electrically conductive matrix. Analysis of the electrochemical properties and biofilm thickness revealed that the diffusion resistance measured using electrochemical impedance spectroscopy might not be due to acetate or proton diffusion limitations to the live layer, but rather electron-mediator diffusion.
阳极生物膜的持续电流产生是生物电化学系统长寿和成功的关键因素。然而，随着时间的推移，阳极生物膜内可能会积累不活跃或死亡的细胞，这对电流产生尤其不利。本文研究了混合和纯培养（Geobacter anodireducens）生物膜随时间变化的电化学性质。对生物膜的三维代谢结构随时间的分析表明，这两种类型的生物膜都形成了一个覆盖死核心的活外层。与其他研究相比，这种双层结构似乎主要是由于阳极电流密度相对较低所致。在生物膜的发展过程中，活层达到了一个恒定的厚度，而死细胞则继续在电极表面附近积累。这一结果表明，只有生物膜的活外层负责电流产生，并表明死内层继续充当导电基质。对电化学性质和生物膜厚度的分析表明，电化学阻抗谱测量的扩散阻力可能不是由于活层中乙酸盐或质子扩散受限，而是电子介质扩散受限。
