Fu Li, Zhou Ting, Wang Jingyuan, You Lexing, Lu Yahai, Yu Linpeng, Zhou Shungui
Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China.
College of Urban and Environmental Sciences, Peking University, Beijing, China.
Front Microbiol. 2019 Mar 5;10:388. doi: 10.3389/fmicb.2019.00388. eCollection 2019.
Magnetite nanoparticles (nanoFeO) have been reported to facilitate direct interspecies electron transfer (DIET) between syntrophic bacteria and methanogens thereby improving syntrophic methanogenesis. However, whether or how nanoFeO affects acetotrophic methanogenesis remain unknown. Herein, we demonstrate the unique role of nanoFeO in accelerating methane production from direct acetotrophic methanogenesis in -enriched cultures, which was further confirmed by pure cultures of Compared with other nanomaterials of higher electrical conductivity such as carbon nanotubes and graphite, nanoFeO with mixed valence Fe(II) and Fe(III) had the most significant stimulatory effect on methane production, suggesting its redox activity rather than electrical conductivity led to enhanced methanogenesis by . Cell morphology and spectroscopy analysis revealed that nanoFeO penetrated into the cell membrane and cytoplasm of . These results provide the unprecedented possibility that nanoFeO in the cell membrane of methanogens serve as electron shuttles to facilitate intracellular electron transfer and thus enhance methane production. This work has important implications not only for understanding the mechanisms of mineral-methanogen interaction but also for optimizing engineered methanogenic processes.
据报道，磁铁矿纳米颗粒（nanoFeO）可促进互营细菌和产甲烷菌之间的直接种间电子转移（DIET），从而改善互营产甲烷作用。然而，nanoFeO是否以及如何影响乙酸营养型产甲烷作用仍不清楚。在此，我们证明了nanoFeO在促进富集培养物中直接乙酸营养型产甲烷作用加速甲烷生成方面的独特作用，这在 的纯培养中得到了进一步证实。与其他具有较高电导率的纳米材料（如碳纳米管和石墨）相比，具有混合价态Fe（II）和Fe（III）的nanoFeO对甲烷生成具有最显著的刺激作用，表明其氧化还原活性而非电导率导致 通过 增强产甲烷作用。细胞形态和光谱分析表明，nanoFeO渗透到 的细胞膜和细胞质中。这些结果提供了得以前所未有的可能性，即产甲烷菌细胞膜中的nanoFeO作为电子穿梭体促进细胞内电子转移，从而提高甲烷生成。这项工作不仅对理解矿物 - 产甲烷菌相互作用的机制具有重要意义，而且对优化工程产甲烷过程也具有重要意义。
