导电性生物炭促进Geobacter和Methanosarcina共培养体系互营产甲烷过程  

Conductive Biochar Stimulates Acetate Conversion to Methane by Syntrophic Interaction between Geobacter and Methanosarcina

作　　者：李坚 汤佳 庄莉 许杰龙 LI Jian;TANG Jia;ZHUANG Li;XU Jielong(Guangzhou Institute of Geochemistry,Chinese Academy of Science,Guangzhou 510640,China;University of Chinese Academy of Sciences,Beijing 100039,China;Guangdong Institute of Eco-Environmental Sciences&Technology,Guangzhou 510650,China;Xiamen Institute of Environmental Sciences,Xiamen 361006,China)

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]中国科学院大学,北京100039 [3]广东省生态环境技术研究所,广东广州510650 [4]厦门市环境科学研究院,福建厦门361006

出　　处：《生态环境学报》2018年第7期1260-1268,共9页Ecology and Environmental Sciences

基　　金：国家自然科学基金项目(31470561);广东省自然科学基金项目(2016A030313779)

摘　　要：近年来研究发现互营氧化产甲烷过程中存在种间直接电子传递(direct interspecies electron transfer,DIET),这种电子传递方式比传统的种间氢转移或种间甲酸转移更为高效。导电生物炭作为导电介质,可以有效促进DIET介导的互营产甲烷进程。乙酸作为有机物厌氧降解的重要中间产物,其降解过程是否存在DIET途径尚不清楚,导电生物炭对乙酸互营降解产甲烷过程的影响机制也未有研究报道。以具有DIET功能的Geobacter sulfurreducens和Methanosarcina barkeri菌株为研究对象,构建共培养体系,以乙酸为电子供体,比较添加不同导电性生物炭共培养体系的甲烷产生和微生物生长情况。结果表明:(1)导电性生物炭处理的产甲烷速率为0.015~0.017 mmol?d^(-1),显著高于对照处理的0.012 mmol?d^(-1);而不导电生物炭处理的产甲烷速率低于对照处理。说明导电性生物炭促进共培养体系中的产甲烷过程,而不具导电性的生物炭没有促进效应;(2)导电性生物炭存在时,共培养体系的甲烷产生速率(0.008 mmol?d^(-1))和产量(0.14 mmol)明显高于Methanosarcina barkeri单菌体系的产甲烷速率(0.006 mmol?d^(-1))和产甲烷量(0.09 mmol),而添加不导电生物炭的共培养体系和单菌体系的甲烷产生速率和产量无明显差异。以上结果表明,导电性生物炭能介导Geobacter sulfurreducens和Methanosarcina barkeri之间的直接电子传递,即Geobacter sulfurreducens氧化乙酸产生的电子,以导电生物炭为导电通道直接传递至Methanosarcina barkeri还原CO2产生甲烷,从而促进乙酸互营氧化产甲烷过程。本研究结果有助于我们理解种间直接电子传递对互营产甲烷过程的贡献及影响效应,为研究甲烷产生的微生物机制提供新的研究思路。In recent years,studies have found that direct interspecies electron transfer(DIET)is a more effective alternative to interspecies hydrogen/formate transfer that occurs in syntrophic methanogenesis.As a conductive medium,conductive biochar can effectively promote DIET-mediated syntrophic methanogensis.Acetate is an important intermediate in the methanogenic degradation of organic matter,however,the possibility of DIET involvement in acetate conversion to methane remains unknown,the mechanism of impact of conductive biochar on acetate-degrading methanogenic process has not been studied yet either.Herein,we investigated the potential of DIET to stimulate methanogenesis in a co-culture of Geobacter sulfurreducens and Methanosarcina barkeri with acetate as the only substrate.The data showed that the methane production rates from conductive biocar amended treatments were 0.015~0.017 mmol·d^-1 which were significantly higher than those of control with methane production rates 0.008 mmol·d^-1.The methane production rate and the cumulative amount in cocultures treated with conductive biochar were 0.008 mmol·d^-1 and 0.14 mmol,respectively,which obviously higher than the cultures of M.barkeri without G.sulfurreducens.Results demonstrated that conductive biochar promotes methanogenesis in co-culture systems,non-conductive biochar has no promoting effect;the methane production rate and yield of the co-culture system with conductive biochar were significantly higher than that of Methanosarcina barkeri,while the co-culture system and single bacteria system of non-conductive biochar had no significant difference in methane production rate and yield.These results suggest that conductive biochar can work as a conductive channel to mediate the direct electron transfer between Geobacter sulfurreducens and Methanosarcina barkeri,in which electrons released from acetate oxidation by Geobacter sulfurreducens are transferred through conductive biochar to Methanosarcina barkeri for CO2 reduction,thereby the process of acetate oxidat

关 键 词：互营产甲烷 乙酸降解 种间直接电子传递 导电性生物炭 

分 类 号：X172[环境科学与工程—环境科学]