Reimers Clare E, Stecher Hilmar A, Westall John C, Alleau Yvan, Howell Kate A, Soule Leslie, White Helen K, Girguis Peter R
College of Oceanic and Atmospheric Sciences, Hatfield Marine Science Center, Oregon State University, Newport, OR 97365, USA.
Appl Environ Microbiol. 2007 Nov;73(21):7029-40. doi: 10.1128/AEM.01209-07. Epub 2007 Aug 31.
The decomposition of marine plankton in two-chamber, seawater-filled microbial fuel cells (MFCs) has been investigated and related to resulting chemical changes, electrode potentials, current efficiencies, and microbial diversity. Six experiments were run at various discharge potentials, and a seventh served as an open-circuit control. The plankton consisted of a mixture of freshly captured phytoplankton and zooplankton (0.21 to 1 mm) added at an initial batch concentration of 27.5 mmol liter(-1) particulate organic carbon (OC). After 56.7 days, between 19.6 and 22.2% of the initial OC remained, sulfate reduction coupled to OC oxidation accounted for the majority of the OC that was degraded, and current efficiencies (of the active MFCs) were between 11.3 and 15.5%. In the open-circuit control cell, anaerobic plankton decomposition (as quantified by the decrease in total OC) could be modeled by three terms: two first-order reaction rate expressions (0.79 day(-1) and 0.037 day(-1), at 15 degrees C) and one constant, no-reaction term (representing 10.6% of the initial OC). However, in each active MFC, decomposition rates increased during the third week, lagging just behind periods of peak electricity generation. We interpret these decomposition rate changes to have been due primarily to the metabolic activity of sulfur-reducing microorganisms at the anode, a finding consistent with the electrochemical oxidization of sulfide to elemental sulfur and the elimination of inhibitory effects of dissolved sulfide. Representative phylotypes, found to be associated with anodes, were allied with Delta-, Epsilon-, and Gammaproteobacteria as well as the Flavobacterium-Cytophaga-Bacteroides and Fusobacteria. Based upon these results, we posit that higher current efficiencies can be achieved by optimizing plankton-fed MFCs for direct electron transfer from organic matter to electrodes, including microbial precolonization of high-surface-area electrodes and pulsed flowthrough additions of biomass.
在双室、充满海水的微生物燃料电池（MFC）中对海洋浮游生物的分解进行了研究，并将其与产生的化学变化、电极电位、电流效率和微生物多样性相关联。在不同的放电电位下进行了六个实验，第七个实验作为开路对照。浮游生物由新鲜捕获的浮游植物和浮游动物（0.21至1毫米）的混合物组成，初始批次浓度为27.5毫摩尔每升颗粒有机碳（OC）。56.7天后，初始OC的19.6%至22.2%仍然存在，与OC氧化耦合的硫酸盐还原占降解的OC的大部分，并且（活性MFC的）电流效率在11.3%至15.5%之间。在开路对照电池中，厌氧浮游生物分解（通过总OC的减少来量化）可以用三个项来建模：两个一级反应速率表达式（在15摄氏度下分别为0.79天⁻¹和0.037天⁻¹）和一个常数、无反应项（占初始OC的10.6%）。然而，在每个活性MFC中，分解速率在第三周增加，仅落后于发电高峰期。我们将这些分解速率变化解释为主要是由于阳极处硫还原微生物的代谢活动，这一发现与硫化物电化学氧化为元素硫以及消除溶解硫化物的抑制作用一致。发现与阳极相关的代表性系统发育型与δ-、ε-和γ-变形菌以及黄杆菌-噬纤维菌-拟杆菌和梭杆菌有关。基于这些结果，我们认为通过优化以浮游生物为食的MFC以实现从有机物到电极的直接电子转移，包括高表面积电极的微生物预定植和脉冲式生物质流加，可以实现更高的电流效率。
