Direct interspecies electron transfer (DIET) from bacteria to methanogens is a revolutionary concept for syntrophic metabolism in methanogenic soils/sediments and anaerobic digestion. Previous studies have indicated that the potential for DIET is limited to methanogens in the Methanosarcinales, leading to the assumption that an abundance of other types of methanogens, such as Methanobacterium species, indicates a lack of DIET. We report here on a strain of Methanobacterium, designated strain YSL, that grows via DIET in defined cocultures with Geobacter metallireducens. The cocultures formed aggregates, in which cells of strain YSL and G. metallireducens were uniformly dispersed throughout. This close association of the two species is the likely explanation for the ability of a strain of G. metallireducens that could not express electrically conductive pili to grow in coculture with strain YSL. Granular activated carbon promoted the initial formation of the DIET-based cocultures. The discovery of DIET in Methanobacterium, the genus of methanogens that has been the exemplar for interspecies electron transfer via H₂, suggests that the capacity for DIET is much more broadly distributed among methanogens than previously considered. More innovative approaches to microbial isolation and characterization are needed in order to better understand how methanogenic communities function.

中文翻译：

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具有直接种间电子转移能力的甲烷杆菌

从细菌到种甲烷源的种间直接电子转移（DIET）是一种在产甲烷土壤/沉积物中的营养代谢和厌氧消化的革命性概念。以前的研究已经表明，对于饮食的潜力被限制在甲烷Methanosarcinales，导致假设其它类型的产甲烷菌，如丰盈甲烷品种，表明缺乏的饮食。我们在这里报告了一种名为Methanobacter的菌株，称为YSL，该菌株通过DIET在与Metallireducens的确定的共培养物中生长。共培养物形成聚集体，其中菌株YSL和G.metallireducens的细胞均匀地分散在各处 这两个物种的这种紧密联系可能解释了不能表达导电菌毛的金属还原杆菌菌株在与YSL菌株共培养中生长的能力。颗粒状活性炭促进了以DIET为基础的共培养物的初步形成。饮食中发现甲烷，已经为种间的电子转移的示例性产甲烷菌属经由ħ ₂，表明对于DIET容量比以前认为甲烷中更广泛地分布。为了更好地了解产甲烷菌群落的功能，需要更多创新的微生物分离和表征方法。