Abstract：
Mechanistic understanding of acetoclastic methanogenesis is pivotal for optimizing anaerobic digestion for efficient methane production. In this study, two different operational modes, continuous flow reactor (CFR) and sequencing batch reactor (SBR), accompanied with solids retention times (SRT) of 10 days (SBR10d and CFR10d) and 25 days (SBR25d and CFR25d) were implemented to elucidate their impacts on microbial communities and energy metabolism of methanogens in acetate-fed systems. Microbial community analysis revealed that the relative abundance of Methanosarcina (16.0%-46.0%) surpassed Methanothrix (3.7%-22.9%) in each reactor. SBRs had the potential to enrich both Methanothrix and Methanosarcina. Compared to SBRs, CFRs had lower total relative abundance of methanogens. Methanosarcina exhibited a superior enrichment in reactors with 10-day SRT, while Methanothrix preferred to be acclimated in reactors with 25-day SRT. The operational mode and SRT were also observed to affect the distribution of acetate-utilizing bacteria, including Pseudomonas, Desulfocurvus, Mesotoga, and Thauera. Regarding enzymes involved in energy metabolism, Ech and Vho/Vht demonstrated higher relative abundances at 10-day SRT compared to 25-day SRT, whereas Fpo and MtrA-H showed higher relative abundances in SBRs than those in CFRs. The relative abundance of genes encoding ATPase harbored by Methanothrix was higher than Methanosarcina at 25-day SRT. Additionally, the relative abundance of V/A-type ATPase (typically for methanogens) was observed higher in SBRs compared to CFRs, while the F-type ATPase (typically for bacteria) exhibited higher relative abundance in CFRs than that in SBRs.
摘要：
对乙酸碎屑甲烷生成的机理理解对于优化厌氧消化以有效生产甲烷至关重要。在这项研究中,两种不同的操作模式，连续流动反应器(CFR)和序批式反应器(SBR),实施了10天（SBR10d和CFR10d）和25天（SBR25d和CFR25d）的固体保留时间（SRT），以阐明其对乙酸盐饲喂系统中产甲烷菌的微生物群落和能量代谢的影响。微生物群落分析显示，每个反应器中甲烷的相对丰度（16.0％〜46.0％）超过甲烷的相对丰度（3.7％〜22.9％）。SBR具有富集甲烷和甲烷的潜力。与SBR相比，CFR的产甲烷菌总相对丰度较低。甲烷弧在具有10天SRT的反应器中表现出优异的富集，而Methanothrix更喜欢在具有25天SRT的反应器中适应。操作模式和SRT也观察到影响利用乙酸的细菌的分布，包括假单胞菌,脱硫菌,Mesotoga,还有Thauera.关于参与能量代谢的酶，与25天SRT相比，Ech和Vho/Vht在10天SRT时表现出更高的相对丰度，而Fpo和MtrA-H在SBR中的相对丰度高于CFR。在25天的SRT时，Methanothrix所携带的编码ATPase的基因的相对丰度高于Methanosarcina。此外,与CFRs相比，SBR中V/A型ATPase（通常用于产甲烷菌）的相对丰度更高，而F型ATPase（通常用于细菌）在CFR中的相对丰度高于SBR。
