Zhang Mou, Han Yilian, Zeng Yuanyuan, Wang Tuo, Wang Ziyuan, Wu Yuhang, Li Nan, Lobo Fernanda Leite, Wang Xin
MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science & Engineering, Nankai University, No. 38 Tongyan Road, Jinnan District, Tianjin 300350, China.
School of Environmental Science and Engineering, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin 300072, China.
Water Res. 2025 Apr 1;273:123084. doi: 10.1016/j.watres.2024.123084. Epub 2024 Dec 31.
Lipids offer high energy recovery potential during anaerobic digestion (AD), but their hydrolysis generates long-chain fatty acids (LCFAs), which are difficult to biodegrade. The introduction of microbial electrolysis cells has been widely recognized as a promising strategy to enhance AD. However, it is still under debate whether the electrical circuit needs to be connected, as certain electrodes with large specific surface areas have been reported to enhance direct interspecies electron transfer (DIET) without requiring an external power supply. Here we confirmed that the carbon brush anode pre-acclimated with electroactive bacteria (EAB) was able to accelerate LCFA methanation. Although the applied potential achieved a rapid methane production, the coupling of homoacetogenesis and electrogenesis consumed part of the bioelectrohydrogen, reducing the maximum methane production rate by 5-13 %. In the AD system with only carbon brushes added, the dominant methanogens shifted from Methanosarcina in solution to Methanothrix on brushes. Pre-enriching EAB further established a composite mechanism, with DIET driven by Syntrophomonas, Geobacter and Methanothrix as the primary pathway, and interspecies hydrogen transfer mediated by Methanospirillum as a complementary process, collectively optimizing LCFA methanation. Genetic regulation underlying microbial tolerance to high LCFA concentrations was then elucidated, underscoring the critical role of combining immobilized electrodes and pre-acclimated EAB in adapting to LCFA stress and improving lipid-rich wastewater treatment.
脂质在厌氧消化（AD）过程中具有较高的能量回收潜力，但其水解会产生难以生物降解的长链脂肪酸（LCFAs）。引入微生物电解池已被广泛认为是一种增强厌氧消化的有前景的策略。然而，对于是否需要连接电路仍存在争议，因为据报道某些具有大比表面积的电极在无需外部电源的情况下可增强种间直接电子转移（DIET）。在此，我们证实预先用嗜电细菌（EAB）驯化的碳刷阳极能够加速长链脂肪酸的甲烷化。尽管施加电势实现了快速产甲烷，但同型产乙酸作用与产电作用的耦合消耗了部分生物电氢，使最大甲烷产率降低了5 - 13%。在仅添加碳刷的厌氧消化系统中，优势产甲烷菌从溶液中的甲烷八叠球菌转变为碳刷上的甲烷丝状菌。预先富集嗜电细菌进一步建立了一种复合机制，以互营单胞菌、地杆菌和甲烷丝状菌驱动的种间直接电子转移作为主要途径，甲烷螺菌介导的种间氢转移作为补充过程，共同优化长链脂肪酸的甲烷化。随后阐明了微生物对高浓度长链脂肪酸耐受性的遗传调控，强调了结合固定化电极和预先驯化的嗜电细菌在适应长链脂肪酸胁迫及改善富脂废水处理方面的关键作用。
