Conductive materials like magnetite nanoparticles (nanoFe₃O₄) are known to stimulate methanogenesis from syntrophic oxidation of butyrate and propionate. Whether conductive materials increase the decomposition of complex organic substrates like plant residues is unknown. Here, we investigated the effects of biochar and nanoFe₃O₄ on anaerobic decomposition of rice straw and methanogenesis in a rice paddy soil. The straw decomposition and CH₄ production were greatly stimulated by both treatments. Major bacterial populations were Bacteroidetes, Clostridia, Deltaproteobacteria, Actinobacteria and Anaerolineae, while methanogens were predominately Methanosarcina, Methanosaeta and Methanobacterium. Bacteroides were relatively enriched in the biochar treatment, while the Deltaproteobacteria and Anaerolineae were favored by nanoFe₃O₄. The relative abundance of typical syntrophs including Syntrophomonas, Syntrophus and Smithella were positively correlated with the degradation of intermediate short-chain fatty acids. Notably, the relative abundance of Geobacter, which increased during the incubation, was approximately tenfold greater than all other syntrophs. The co-occurrence of Geobacter together with Methanosarcina and Methanosaeta suggests that the enhanced decomposition of rice straw and methanogenesis by biochar and magnetite may be related to direct interspecies electron transfer involved in the syntrophic oxidation of intermediate products.

已知诸如磁铁矿纳米颗粒（nanoFe ₃ O ₄）的导电材料可刺激丁酸酯和丙酸酯的共养氧化而促进甲烷生成。导电材料是否会增加复杂的有机底物（如植物残渣）的分解尚不清楚。在这里，我们调查了生物炭和nanoFe ₃ O ₄对稻草厌氧分解和稻田土壤甲烷化的影响。两种处理均极大地促进了秸秆的分解和CH _4的产生。主要细菌种群是拟杆菌，梭状芽孢杆菌，变形杆菌，放线菌和Anaerolineae，而甲烷是主要甲烷，Methanosaeta和甲烷。细菌化物在生物炭处理中相对富集，而DeltaProteobacteria和厌氧菌则受到nanoFe ₃ O _4的青睐。典型syntrophs包括的相对丰度Syntrophomonas，Syntrophus和Smithella用的中间短链脂肪酸的降解呈正相关。值得注意的是，地细菌的相对丰度在温育过程中增加，大约是所有其他同食物的十倍。的同现地杆菌连同甲烷八叠球菌和Methanosaeta表明由生物炭和磁铁矿稻草和产甲烷的增强分解，可能与直接种间电子参与中间产品的互养氧化传输。