Extracellular electron transfer between syntrophic partners needs to be efficiently maintained in methanogenic environments. Direct extracellular electron transfer via electrical current is an alternative to indirect hydrogen transfer but requires construction of conductive extracellular structures. Conductive mechanisms and relationship between conductivity and the community composition in mixed-species methanogenic biofilms are not well understood. The present study investigated conductive behaviors of methanogenic biofilms and examined the correlation between biofilm conductivity and community composition between different anaerobic biofilms enriched from the same inoculum. Highest conductivity observed in methanogenic biofilms was 71.8 ± 4.0 μS/cm. Peak-manner response of conductivity upon changes over a range of electrochemical potentials suggests that electron transfer in methanogenic biofilms occurs through redox driven super-exchange. The strong correlation observed between biofilm conductivity and Geobacter spp. in the metabolically diverse anaerobic communities suggests that the efficiency of DEET may provide pressure for microbial communities to select for species that can produce electrical conduits.

在产甲烷环境中，需要有效地维持同养伴侣之间的细胞外电子转移。通过进行直接的细胞外电子转移电流是间接氢转移的替代方法，但需要构造导电的细胞外结构。在混合物种产甲烷生物膜中的导电机理以及电导率与群落组成之间的关系尚不十分清楚。本研究调查了产甲烷生物膜的导电行为，并研究了从同一接种物中富集的不同厌氧生物膜之间生物膜电导率与群落组成之间的相关性。在产甲烷生物膜中观察到的最高电导率为71.8±4.0μS/ cm。电导率在一系列电化学电势变化时的峰-峰响应表明，产甲烷生物膜中的电子转移是通过氧化还原驱动的超交换发生的。观察到生物膜电导率与土杆菌属。在代谢多样性的厌氧菌群落中的研究表明，DEET的效率可能为微生物群落选择可以产生电导管的物种提供压力。