Wang Zhongzhong, Wang Shun, Hu Yuansheng, Du Bang, Meng Jizhong, Wu Guangxue, Liu He, Zhan Xinmin
Civil Engineering, College of Science and Engineering, National University of Ireland, Galway, Ireland; Ryan Institute, National University of Ireland, Galway, Ireland; MaREI Center for Marine and Renewable Energy, National University of Ireland, Galway, Ireland.
Civil Engineering, College of Science and Engineering, National University of Ireland, Galway, Ireland; Ryan Institute, National University of Ireland, Galway, Ireland.
Water Res. 2022 Oct 1;224:119029. doi: 10.1016/j.watres.2022.119029. Epub 2022 Aug 29.
A shift from the acetoclastic to the hydrogenotrophic pathway in methanogenesis under ammonia inhibition is a common observation in anaerobic digestion. However, there are still considerable knowledge gaps concerning the differential ammonia tolerance of acetoclastic and hydrogenotrophic methanogens (AMs and HMs), their responses to different ammonia species (NH, NH), and their recoverability after ammonia inhibition. With the successful enrichment of mesophilic AMs and HMs cultures, this study aimed at addressing the above knowledge gaps through batch inhibition/recovery tests and kinetic modeling under varying total ammonia (TAN, 0.2-10 g N/L) and pH (7.0-8.5) conditions. The results showed that the tolerance level of HMs to free ammonia (FAN, IC=1345 mg N/L) and NH (IC=6050 mg N/L) was nearly 11 times and 3 times those of AMs (NH, IC=123 mg N/L; NH, IC=2133 mg N/L), respectively. Consistent with general belief, the AMs were more impacted by FAN. However, the HMs were more adversely affected by NH when the pH was ≤8.0. A low TAN (1.0-4.0 g N/L) could cause irreversible inhibition of the AMs due to significant cell death, whereas the activity of HMs could be fully or even over recovered from severe ammonia stress (FAN≤ 0.9 g N/L or TAN≤10 g N/L; pH ≤8.0). The different tolerance responses of AMs and HMs might be associated with the cell morphology, multiple energy-converting systems, and Gibbs free energy from substrate-level phosphorylation.
在厌氧消化过程中，氨抑制条件下甲烷生成途径从乙酸裂解型转变为氢营养型是常见现象。然而，关于乙酸裂解型和氢营养型产甲烷菌（AMs和HMs）对氨的不同耐受性、它们对不同氨形态（NH₃、NH₄⁺）的响应以及氨抑制后它们的恢复能力，仍存在相当大的知识空白。随着嗜温AMs和HMs培养物的成功富集，本研究旨在通过在不同总氨（TAN，0.2 - 10 g N/L）和pH（7.0 - 8.5）条件下的批次抑制/恢复试验和动力学建模来填补上述知识空白。结果表明，HMs对游离氨（FAN，IC₅₀ = 1345 mg N/L）和NH₄⁺（IC₅₀ = 6050 mg N/L）的耐受水平分别是AMs（NH₃，IC₅₀ = 123 mg N/L；NH₄⁺，IC₅₀ = 2133 mg N/L）的近11倍和3倍。与普遍看法一致，AMs受FAN的影响更大。然而，当pH≤8.0时，HMs受NH₄⁺的不利影响更大。低TAN（1.0 - 4.0 g N/L）会因大量细胞死亡导致AMs受到不可逆抑制，而HMs的活性在严重氨胁迫（FAN≤0.9 g N/L或TAN≤10 g N/L；pH≤8.0）后可以完全甚至过度恢复。AMs和HMs不同的耐受反应可能与细胞形态、多种能量转换系统以及底物水平磷酸化产生的吉布斯自由能有关。
