Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, 266237, Shandong, China.
Suzhou Research Institute, Shandong University, Suzhou, 215123, Jiangsu, China.
Microb Ecol. 2023 Nov;86(4):2970-2980. doi: 10.1007/s00248-023-02294-8. Epub 2023 Sep 9.
Biochar can be applied to diverse natural and engineered anaerobic systems. Biochar plays biogeochemical roles during its production, storage, and environmental dynamics, one of which is related to the global methane flux governed by methanotrophs and methanogens. Our understanding of relevant mechanisms is currently limited to the roles of biochar in methanotrophic growth, but less is known about the roles of biochar in methanogenic growth. Here, we demonstrated that biochar enhanced the methanogenic growth of a model methanogen, Methanosarcina acetivorans, and the role of biochar as an electron acceptor during methanogenic growth was confirmed, which is referred to as biochar-respiratory growth. The biochar-respiratory growth of M. acetivorans promoted the secretion of extracellular polymeric substances (EPS) with augmented electron transfer capabilities, and the removal of EPS significantly attenuated extracellular electron transfer. Identification and quantification of prosthetic cofactors for EPS suggest an important role of flavin and F in extracellular electron transfer. Transcriptomic analysis provided additional insights into the biochar-respiratory growth of M. acetivorans, showing that there was a positive response in transcriptional regulation to the favorable growth environment provided by biochar, which stimulated global methanogenesis. Our results shed more light on the in situ roles of biochar in the ecophysiology of methanogens in diverse anaerobic environments.
生物炭可应用于多种自然和工程化的厌氧系统。在其生产、储存和环境动态过程中，生物炭发挥着生物地球化学作用，其中之一与受甲烷营养菌和产甲烷菌控制的全球甲烷通量有关。我们对相关机制的理解目前仅限于生物炭在甲烷营养生长中的作用，但对生物炭在产甲烷生长中的作用知之甚少。在这里，我们证明了生物炭增强了模式产甲烷菌 Methanosarcina acetivorans 的产甲烷生长，并且确认了生物炭在产甲烷生长过程中作为电子受体的作用，这被称为生物炭呼吸生长。M. acetivorans 的生物炭呼吸生长促进了具有增强电子传递能力的细胞外聚合物物质（EPS）的分泌，而 EPS 的去除显著减弱了细胞外电子传递。对 EPS 中类菌体辅因子的鉴定和定量表明黄素和 F 在细胞外电子传递中具有重要作用。转录组分析为 M. acetivorans 的生物炭呼吸生长提供了更多的见解，表明生物炭提供的有利生长环境在转录调控中存在积极的响应，从而刺激了全局产甲烷作用。我们的研究结果更深入地了解了生物炭在不同厌氧环境中甲烷菌生理生态学中的原位作用。
