Magnetite Particles Triggering a Faster and More Robust Syntrophic Pathway of Methanogenic Propionate Degradation
Magnetite Particles Triggering a Faster and More Robust Syntrophic Pathway of Methanogenic Propionate Degradation
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DOI：
10.1021/es5016789
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发表时间：
2014-07-01
影响因子：
11.4
通讯作者：
Aulenta, Federico
中科院分区：
文献类型：
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作者：
Viggi, Carolina Cruz;Rossetti, Simona;Aulenta, Federico
细菌和古细菌之间的种间电子转移机制在自然和工程厌氧生态系统中有机物的产甲烷降解过程中发挥着关键作用。越来越多的证据表明，在互养群落中，电子转移并不完全依赖于可扩散分子和能量载体（例如氢或甲酸盐）的交换，而是微生物具有以更直接的方式交换代谢电子的能力。在这里，我们表明，向产甲烷污泥中添加微米大小的磁铁矿 (Fe3O4) 颗粒可以提高丙酸盐的甲烷生产率（高达 33%），丙酸盐是有机物厌氧消化的关键中间体，也是研究能量限制互养群落的模型底物。这种刺激作用很可能是由于直接种间电子转移（DIET）的建立而产生的，该转移基于磁铁矿颗粒作为丙酸氧化产乙酸菌和二氧化碳还原产甲烷菌之间的电子导管。理论计算表明，DIET 允许电子在互养伙伴之间转移，其速率远高于通过种间 H-2 转移所能达到的速率。除了改善厌氧消化的巨大潜力（这是一种经过验证的可再生能源生产生物策略）之外，本文描述的基于传导的 DIET 还可以在富含磁铁矿的土壤和沉积物的自然甲烷排放中发挥作用。
Interspecies electron transfer mechanisms between Bacteria and Archaea play a pivotal role during methanogenic degradation of organic matter in natural and engineered anaerobic ecosystems. Growing evidence suggests that in syntrophic communities electron transfer does not rely exclusively on the exchange of diffusible molecules and energy carriers such as hydrogen or formate, rather microorganisms have the capability to exchange metabolic electrons in a more direct manner. Here, we show that supplementation of micrometer-size magnetite (Fe3O4) particles to a methanogenic sludge enhanced (up to 33%) the methane production rate from propionate, a key intermediate in the anaerobic digestion of organic matter and a model substrate to study energy-limited syntrophic communities. The stimulatory effect most probably resulted from the establishment of a direct interspecies electron transfer (DIET), based on magnetite particles serving as electron conduits between propionate-oxidizing acetogens and carbon dioxide-reducing methanogens. Theoretical calculations revealed that DIET allows electrons to be transferred among syntrophic partners at rates which are substantially higher than those attainable via interspecies H-2 transfer. Besides the remarkable potential for improving anaerobic digestion, which is a proven biological strategy for renewable energy production, the herein described conduction-based DIET could also have a role in natural methane emissions from magnetite-rich soils and sediments.