Zhang Pengshuai, Zhang Jingxin, Zhang Tengyu, Chen Jiaqi, Yang Qing, He Yiliang, Tong Yen Wah
China-UK Low Carbon College, Shanghai Jiao Tong University, Shanghai 200240, China; School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Carbon-Negative Synthetic Biology for Biomaterial Production from CO2 (CNSB), Campus for Research Excellence and Technological Enterprise (CREATE), 1 CREATE Way, Singapore 138602 Singapore.
China-UK Low Carbon College, Shanghai Jiao Tong University, Shanghai 200240, China; Carbon-Negative Synthetic Biology for Biomaterial Production from CO2 (CNSB), Campus for Research Excellence and Technological Enterprise (CREATE), 1 CREATE Way, Singapore 138602 Singapore.
Waste Manag. 2025 Aug 1;204:114925. doi: 10.1016/j.wasman.2025.114925. Epub 2025 Jun 10.
In anaerobic digestion (AD), stressed conditions often shift methanogenesis from acetoclastic to less efficient syntrophic acetate oxidation (SAO) coupled with hydrogenotrophic methanogenesis (HM). Biochar has been shown to enhance the efficiency of SAO by facilitating direct interspecies electron transfer. However, the mechanisms underlying electron transfer at the micro-interface remain unclear, limiting its broader application. To address this uncertainty, this study investigates the role of electron hopping behavior at the biochar-microbe interface, focusing on interfacial electron transfer and calculations based on electron hopping theory. Consequently, electrochemical analyses and microscopy-Raman spectroscopy revealed that microbiomes attached to biochar surfaces might engage in electron hopping via cytochrome c (Cytc) and riboflavin in extracellular polymers. Molecular dynamics simulations and theoretical calculations further substantiated the role of electron hopping in the biochar induced methanogenesis pathway. The minimum distance for redox hopping units decreased from 13.37 to 10.52 nm in promoted SAO, facilitating electron hopping. Additionally, biochar serves as an electron acceptor through electron tunneling, thereby enhancing electron hopping. Notably, the higher heterogeneous electron transfer rate constant (k) for biochar prepared at 800 °C suggests that its superior conductive carbon matrix significantly enhances electron hopping. In light of these findings, this study proposed that electron hopping could be stimulated by biochar through shortening the molecular redox unit distance, thereby facilitating the efficient progression of SAO-HM.
在厌氧消化（AD）过程中，压力条件常常使甲烷生成从乙酸裂解转变为效率较低的与氢营养型甲烷生成（HM）耦合的互营乙酸氧化（SAO）。生物炭已被证明可通过促进种间直接电子转移来提高SAO的效率。然而，微界面处电子转移的潜在机制仍不清楚，这限制了其更广泛的应用。为了解决这一不确定性，本研究调查了生物炭-微生物界面处电子跳跃行为的作用，重点关注界面电子转移以及基于电子跳跃理论的计算。因此，电化学分析和显微镜-拉曼光谱显示，附着在生物炭表面的微生物群落可能通过细胞色素c（Cytc）和细胞外聚合物中的核黄素进行电子跳跃。分子动力学模拟和理论计算进一步证实了电子跳跃在生物炭诱导的甲烷生成途径中的作用。在促进的SAO中，氧化还原跳跃单元的最小距离从13.37纳米降至10.52纳米，促进了电子跳跃。此外，生物炭通过电子隧穿作为电子受体，从而增强电子跳跃。值得注意的是，在800℃制备的生物炭具有更高的异质电子转移速率常数（k），这表明其优异的导电碳基质显著增强了电子跳跃。基于这些发现，本研究提出生物炭可通过缩短分子氧化还原单元距离来刺激电子跳跃，从而促进SAO-HM的高效进行。
