Methanogenesis facilitated by electric syntrophy via (semi)conductive iron-oxide minerals
Methanogenesis facilitated by electric syntrophy via (semi)conductive iron-oxide minerals
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DOI：
10.1111/j.1462-2920.2011.02611.x
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发表时间：
2012-07-01
影响因子：
5.1
通讯作者：
Watanabe, Kazuya
中科院分区：
文献类型：
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作者：
Kato, Souichiro;Hashimoto, Kazuhito;Watanabe, Kazuya
甲烷生成是全球碳循环的重要组成部分，也是可持续能源的关键生物过程。从有机物中产甲烷是通过不同微生物物种之间的互养相互作用来实现的，其中经由扩散载体（例如氢和甲酸盐）的种间电子传递（IET）已知是瓶颈步骤。我们在此报告，土壤微生物与（半）导电氧化铁矿物质的补充，创造独特的种间相互作用，促进产甲烷。以乙酸盐或乙醇为基质，在添加或不添加（半）导电氧化铁（赤铁矿或磁铁矿）的条件下，从稻田土壤中富集产甲烷微生物。我们发现，补充这些铁氧化物中的任一种导致在滞后时间和生产速率方面的甲烷生成的加速，而补充绝缘氧化铁（水铁矿）则没有。从富集培养物PCR扩增的16S rRNA基因片段的克隆文库分析显示，氧化铁的补充刺激了Geophylla spp的生长。此外，甲烷生成的特异性抑制剂的添加抑制了Geophysicspp的生长。这些结果表明，Geophylla生长在与产甲烷菌的互养关系下，IET可以通过电流通过（半）导电氧化铁矿物（称为电互养）发生。鉴于导电矿物在自然界中无处不在，这种高能相互作用可能广泛存在于土壤和沉积物中，并可用于开发高效的生物能源过程。
Methanogenesis is an essential part of the global carbon cycle and a key bioprocess for sustainable energy. Methanogenesis from organic matter is accomplished by syntrophic interactions among different species of microbes, in which interspecies electron transfer (IET) via diffusive carriers (e.g. hydrogen and formate) is known to be the bottleneck step. We report herein that the supplementation of soil microbes with (semi)conductive iron-oxide minerals creates unique interspecies interactions and facilitates methanogenesis. Methanogenic microbes were enriched from rice paddy field soil with either acetate or ethanol as a substrate in the absence or presence of (semi)conductive iron oxides (haematite or magnetite). We found that the supplementation with either of these iron oxides resulted in the acceleration of methanogenesis in terms of lag time and production rate, while the supplementation with an insulative iron oxide (ferrihydrite) did not. Clone-library analyses of 16S rRNA gene fragments PCR-amplified from the enrichment cultures revealed that the iron-oxide supplementation stimulated the growth of Geobacter spp. Furthermore, the addition of a specific inhibitor for methanogenesis suppressed the growth of Geobacter spp. These results suggest that Geobacter grew under syntrophic association with methanogens, and IET could occur via electric currents through (semi)conductive iron-oxide minerals (termed electric syntrophy). Given the ubiquity of conductive minerals in nature, such energetic interactions may occur widely in soil and sediments and can be used to develop efficient bioenergy processes.