引用本文:黄玲艳,刘 星,周顺桂.微生物直接种间电子传递:机制及应用[J].土壤学报,2018,55(6):1313-1324.
Huang Lingyan,LIU Xing,ZHOU Shungui.Direct Interspecies Electron Transfer of Microbes: Mechanism and Application[J].Acta Pedologica Sinica,2018,55(6):1313-1324
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微生物直接种间电子传递:机制及应用
黄玲艳,刘星,周顺桂
福建农林大学,福建农林大学,福建农林大学
摘要:
微生物种间电子传递(Interspecies electron transfer,IET)是指电子供体微生物与电子受体微生物之间通过直接或间接方式传递电子形成互营生长关系,从而共同完成单一微生物不能完成的代谢过程的现象。IET分为间接种间电子传递(Mediated IET,MIET)和直接种间电子传递(Direct IET,DIET)。其中,前者一般需要氢、甲酸、核黄素等作为电子载体,而后者是指微生物间通过纳米导线、氧化还原蛋白、导电颗粒等进行直接电子交换。DIET是最新发现的IET方式,DIET的发现改变了微生物互营代谢必须依赖氢/甲酸等能量载体的传统认识。本文在论述MIET的同时,重点阐述了DIET的三种介导机制,列举了参与IET的典型微生物种类,系统介绍了IET在厌氧消化产甲烷、甲烷厌氧氧化、微生物脱氯等重要环境过程中的作用机制及应用潜力,并展望了微生物种间电子传递的未来研究方向。本综述有助于加深对微生物IET发生机制的认识,为理解微生物IET在自然界碳氮等元素循环、温室气体排放、污染物降解等关键生物地球化学过程中的作用提供理论基础,为IET的实际工程应用提供可能。
关键词:  种间电子传递  直接种间电子传递  纳米导线  氧化还原蛋白  厌氧消化
DOI:10.11766/trxb201805240172
分类号:
基金项目:国家自然科学基金项目(91751109, 41671264, 31600089)
Direct Interspecies Electron Transfer of Microbes: Mechanism and Application
Huang Lingyan,Liu xing and Zhou shungui
Fujian Agriculture and Forestry University,Fujian Agriculture and Forestry University,Fujian Agriculture and Forestry University
Abstract:
Microbial interspecies electron transfer (IET) refers to the electron exchange between electron-donating microorganisms and electron-accepting microorganisms that forms a syntrophic growth relationship between the two thus enabling the two to jointly accomplish a certain metabolic process that no single microorganism can do. Moreover, it also plays a significant role in biogeochemical processes, such as degradation of organic matter, production of bioenergy and reduction of greenhouse gas emission. IET could be sorted into direct IET (DIET) and indirect or mediated IET (MIET). DIET occurs when there is a biological electrical connection and a difference in voltage potential, whereas MIET relies on diffusion of redox carriers driven by concentration gradients. Generally MIET needs hydrogen, formate or flavin as electron carrier, while DIET is found done directly through nanowire (e-pili), redox protein or conductive particles. Interspecies hydrogen/formate transfer, one type of MIET, occurs commonly in methanogenic microbial community, such as S organism and Methanobacterium ruminantium, Desulfovibrio vulgaris and Methanosarcina barkeri. In addition, sulfide, L-cysteine and AQDS can act as electron shuttles mediating electron transfer between microorganisms, such as Desulfuromonas acatoxidans and Prosthecochloris aestuarii. However, electron transfer between Geobacter species so far has only been documented to be direct: by way of e-pili and c-type cytochromes. Either of these Geobacter cells short of biological connections, such as e-pili and (or) cytochromes, can not get syntrophically related. Nevertheless, with the mediation of conductive materials, such as activated carbon and biochar, e-pili would become less functional during the process of DIET since syntrophic partners could exchange electrons via these conductive carbon materials. Moreover, conductive mineral magnetite can substitute for outer-membrane c-type cytochrome in its role. Mutant strain of G. sulfurreducens that is deficient in OmcS cannot co-culture with G. metallireducens, but with the addition of magnetites they can exchange electrons successfully. The discovery of DIET has changed the tradition gnosia that microbial syntrophic metabolism would not occur without energy carriers, such as hydrogen and formate, and has opened up a new scientific perspective for understanding biogeochemical processes, such as circulation of C/N/S, emissions of greenhouse and degradation of pollutants. The core of microbial IET is electron transfer between microbes. Further studies should be done on mechanism of IET and new effective IET microorganisms in order to put IET into practical engineering application. However, the researches on tmechanism of IET between microbes, at present, are still in their preliminary stage and so have a number of problems to be solved, for example, how exactly electron transfer occurs between microorganisms, whether there is any microorganism more IET efficient, and if there is any method that can more economically and efficiently accelerate IET, etc. In this review, the mechanisms of MIET is summarized, meanwhile, the three mediating mechanisms for DIET are expounded emphatically. Representative microbes participating in IET are introduced. Potential applications of IET to environment processes such as methane-producing anaerobic digestion, anaerobic methane oxidation and dechlorination are proposed and directions of future researches on IET discussed.
Key words:  Interspecies electron transfer  Direct interspecies electron transfer  Nanowire  Redox proteins  Anaerobic digestion