微生物互营产甲烷研究进展

Microbial syntrophic methanogenesis:a review

甲烷是仅次于二氧化碳的第二大温室气体,也是典型的可再生资源.目前大气中的甲烷约有74%来自微生物互营产甲烷过程.研究微生物互营产甲烷对于控制全球气候变暖和发展清洁能源都具有重要意义.本文主要对产甲烷菌的类型、互营产甲烷的过程、电子传递等方面进行综述.典型的有机物厌氧互营氧化要经历3个步骤,主要由3种不同的菌群完成,即发酵菌、互营菌和产甲烷菌.互营产甲烷过程释放的能量很低.在互营产甲烷过程中存在互营菌的种内电子传递和互营菌与产甲烷菌的种间电子传递.反向电子传递是互营菌种内电子传递的一种方式,表现为电子歧化和电子聚合,都需要消耗能量使得热力学上不利的氧化还原反应得以发生.种间电子传递包括种间氢气转移、种间甲酸转移和种间直接电子传递3种方式.未来人们可以利用基因敲除、高通量测序、计算生物学等方法研究互营微生物间底物和电子的传递,以及互营菌群对环境变化的响应机制,以便将互营产甲烷过程应用于实际生产.

Methane is the second most important greenhouse gas as well as a typical renewable biomass energy.Currently,about 74%of the methane in the atmosphere originates from the microbial syntrophic mehanogenesis process.Research on microbial syntrophic methanogenesis is therefore very important for controlling global warming and developing clean energy.This paper mainly reviews the types of methanogens,the process of syntrophic methanogenesis and its electron transfer.The typical anaerobic syntrophic oxidation of organic matters consists of three steps that are mainly conducted by fermenting bacteria,syntrophic bacteria,and methanogens.The energy released during syntrophic methanogenesis is extremely low.The syntrophic methanogenesis process contains intraspecies electron transfer in syntrophic bacteria and interspecies electron transfer between syntrophic bacteria and methanogens.Reverse electron transfer exists in intraspecies electron transfer in syntrophic bacteria and displays as electron bifurcation and electron confurcation which both require energy input to drive critical redox reactions.Interspecies electron transfer includes three types：interspecies hydrogen transfer（IHT）,interspecies formate transfer（IFT） and direct interspecies electron transfer（DIET）.In the future,in order to apply the process of syntrophic methanogenesis into practice,methods of gene knockout,high through-put sequencing and computational biology could be utilized for the study of substrate and electron transfer between syntrophic microbes and the response of syntrophic microbes to the environmental changes.