Ammonia is a ubiquitous potential inhibitor of anaerobic digestion processes, mainly exhibiting inhibition towards methanogenic activity. However, knowledge as to how ammonia affects the methanogens is still limited. In this study, we cultured a multitrophic methanogen, Methanosarcina barkeri DSM 800, with acetate, H₂/CO₂, and methanol to evaluate the influence of ammonia on different methanogenic pathways. Aceticlastic methanogenesis was more sensitive to increased ammonia concentrations than hydrogenotrophic and methylotrophic methanogenesis. Theoretical maximum NH₃ tolerances of M. barkeri fed with acetate, H₂/CO₂, and methanol were calculated to be 39.1 ± 9.0, 104.3 ± 7.4, and 85.7 ± 1.0 mg/L, respectively. The order of the ΔG range of M. barkeri under three methanogenic pathways reflected the order of ammonia tolerance of M. barkeri. Our results provide insights into the role of the thermodynamic potential of methanogenesis on the tolerance of ammonia stress; and shed light on the mechanism of ammonia inhibition on anaerobic digestion.

氨是一种普遍存在的潜在厌氧消化过程抑制剂，主要表现出对产甲烷活性的抑制作用。然而，关于氨如何影响产甲烷菌的知识仍然有限。在这项研究中，我们用乙酸盐、H ₂ /CO _{2和甲醇培养了一种多营养型产甲烷菌}Methanosarcina barkeri DSM 800，以评估氨对不同产甲烷途径的影响。Aceticlastic 产甲烷比氢营养型和甲基营养型产甲烷对增加的氨浓度更敏感。M. barkeri的理论最大 NH ₃耐受性，喂食醋酸盐，H ₂ /CO ₂和甲醇的计算值分别为 39.1 ± 9.0、104.3 ± 7.4 和 85.7 ± 1.0 mg/L。三种产甲烷途径下巴氏杆菌ΔG范围的大小顺序反映了巴氏杆菌耐氨性的大小顺序。我们的研究结果提供了关于产甲烷的热力学潜力对氨胁迫耐受性的作用的见解；并阐明氨抑制厌氧消化的机制。