Biological Iron-Monosulfide Production for Efficient Electricity Harvesting from a Deep-Sea Metal-Reducing Bacterium
Biological Iron-Monosulfide Production for Efficient Electricity Harvesting from a Deep-Sea Metal-Reducing Bacterium
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DOI：
10.1002/cbic.200900775
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发表时间：
2010-03-22
期刊：
影响因子：
3.2
通讯作者：
Hashimoto, Kazuhito
中科院分区：
文献类型：
--
作者：
Nakamura, Ryuhei;Okamoto, Akihiro;Hashimoto, Kazuhito
微生物通过利用多种代谢策略生活在广泛的自然环境中，并能够进行大多数热力学上可能的氧化还原反应，以获得生长所需的能量目前对自然资源枯竭的担忧增加了了解微生物固有的聪明才智的需要，并寻找利用（或复制）它们的新陈代谢来利用可再生能源的方法。[1,2]在此，我们报道了生物生产单相一硫化铁（mackinawite），用于在电化学电池中有效收集细菌代谢的电子。硫化铁（FeS），如麦氏铁矿、灰长铁矿、马氏铁矿和黄铁矿，是在缺氧海洋环境中普遍存在的丰富矿物，是微生物代谢的副产品或地热活动的结果据报道，与微生物与FeSs相互作用相关的几个生物地球化学过程[2-4]，在热液喷口周围发现了高度活跃的生物圈，说明了FeSs作为隔绝太阳辐射环境中微生物活动的能量来源的重要性。[2b， 3]此外，FeSs的许多生物学功能，[3b]包括结构支撑、抗菌剂、磁性、光学和重力传感装置，已经被确定；这凸显了利用细胞表面相关的纳米FeSs存在的多种微生物机制。虽然纳米FeSs的生物矿化是一个众所周知的现象[2d， 3,4]，但只有少数先前的研究从电子传导特性的角度考虑其生物学功能。FeSs具有广泛的成分和结构，满足固态电池、电催化、光伏和其他工业应用所需的各种电化学功能。[2d, 3d， 4c]为了进一步探索微生物的独创性，了解FeSs在微生物代谢和电子传递中的重要性，我们研究了铁还原细菌Shewanella loihica PV-4对FeSs的生物矿化作用，该细菌最初是从深海热液口（海平面以下1325 m）附近的富铁微生物席中分离出来的本研究表明，s.l oihica PV-4具有利用生物合成的单硫化铁（FeS）的Fe三维电子作为细胞外远距离电子转移管道的能力。自组织、导电的细胞- fes组件使微生物电流的产生比缺乏生物矿物质的细胞培养高出两个数量级。在含铁离子（FeCl3）和硫代硫酸盐（Na2S2O3）为终端电子受体，乳酸为碳源和供电子化合物的培养基中，在258C厌氧培养S. loihica PV-4细胞。[3e， 7]细胞悬浮液瞬间由黄色变为棕色，接种约5h后产生黑色沉淀。添加细胞前的黄色沉淀物的x射线衍射（XRD）图显示一个宽的未定义区域，没有明显的峰（图1，底部）。然而，与细胞孵育后，在XRD图中出现了几个峰，这些峰被分配给单质硫(S)，针铁矿（α-FeOOH）和mackinawite （FeS；图1,1天）。[3d]单质硫和针铁矿的峰强度都随着孵育时间的增加而降低，而观察到mackinawite的峰强度也随之增加。扫描电镜观察（图2）结合共聚焦显微镜观察gfp标记的细胞（图2）显示…
Micro-organisms inhabit a broad range of natural environments through the exploitation of multiple metabolic strategies and are able to perform most thermodynamically possible redox reactions to obtain energy for their growth.[1] Present concerns about the depletion of natural resources has increased the need to understand inherent microbial ingenuities, and search for methodologies for utilizing (or replicating) their metabolism to harness renewable sources of energy.[1, 2] Herein, we report the biological production of single-phase iron monosulfide (mackinawite) for efficient harvesting of bacterial metabolized electrons in electrochemical cells. Iron sulfides (FeS), such as mackinawite, greigite, marcasite, and pyrite, are ubiquitous and abundant minerals in anoxic marine environments formed as by-products of microbial metabolism or a consequence of geothermal activity.[3] Several biogeochemical processes associated with microbial interaction with FeSs have been reported,[2–4] with the discovery of highly active biospheres around hydrothermal vents illustrating the significance of FeSs as an energy source for microbial activities in environments isolated from solar irradiation.[2b, 3] Moreover, a number of biological functions of FeSs,[3b] including structural support, antimicrobial agents, and magnetic-, optical-, and gravity-sensing devices, have been identified; this highlights the diverse microbial mechanisms that exist for harnessing cell-surface-associated nanosized FeSs. Although the biomineralization of nanosized FeSs is a wellknown phenomenon,[2d, 3, 4] only a few previous studies [4] have considered its biological function from the view point of electron-conducting properties. FeSs have a wide range of compositions and structures, fulfilling the diverse electrochemical functionalities required for solid-state batteries, electrocatalysis, photovoltaics, and other industrial applications.[2d, 3d, 4c] In an effort to further explore microbial ingenuity and understand the importance of FeSs in microbial metabolism and electron transfer, we examined the biomineralization of FeSs by the Fereducing bacterium Shewanella loihica PV-4, which was originally isolated from iron-rich microbial mats near a deep-sea hydrothermal vent (1325 m below sea level).[5] This study demonstrated that S. loihica PV-4 has the ability to exploit the Fe 3d electrons of biologically synthesized iron monosulfide (FeS) as extracellular long-distant electron-transfer conduits. Self-organizing, electrically conducting cell–FeS assemblies enabled the generation of a microbial current two orders of magnitude higher than in cell cultures lacking the biogenic minerals. S. loihica PV-4 cells were cultured anaerobically at 258C in a medium containing both ferric ions (FeCl3) and thiosulfate (Na2S2O3) as terminal electron acceptors, and lactate as a carbon source and electron-donating compound.[3e, 7] The cell suspension instantly turned from yellow to brown, and a black precipitate was generated after approximately 5 h of inoculation. The X-ray diffraction (XRD) pattern of the yellow precipitate present before the addition of cells showed a broad undefined region with no significant peaks (Figure 1, bottom). Upon incubation with cells, however, several peaks appeared in the XRD pattern, which were assigned to elemental sulfur (S), goethite (α-FeOOH), and mackinawite (FeS; Figure 1, 1 day).[3d] The peak intensities for both elemental sulfur and goethite decreased with increasing incubation times, while a concomitant increase in the peaks assigned to mackinawite was observed. SEM observations (Figure 2) combined with confocal microscopy on GFP-labeled cells (FigureS2) showed …