Department of Bioenvironmental Systems Engineering, National Taiwan University, Taiwan.
Department of Agronomy, National Taiwan University, Taiwan.
Chemosphere. 2022 Feb;289:133049. doi: 10.1016/j.chemosphere.2021.133049. Epub 2021 Nov 25.
Understanding the environmental niche segregation of ammonia-oxidizing archaea (AOA) and bacteria (AOB) and its impact on their relative contributions to nitrification and nitrous oxide (NO) production is essential for predicting NO dynamics within an ecosystem. Here, we used ammonia oxidizer-specific inhibitors to measure the differential contributions of AOA and AOB to potential ammonia oxidization (PAO) and NO fluxes over pH (4.0-9.0) and temperature (10-45 °C) gradients in five soils and three wetland sediments. AOA and AOB activities were differentiated using PTIO (2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide), 1-octyne, and acetylene. We used square root growth (SQRT) and macromolecular rate theory (MMRT) models to estimate cardinal temperatures and thermodynamic characteristics for AOA- and AOB-dominated PAO and NO fluxes. We found that AOA and AOB occupied different niches for PAO, and soil temperature was the major determinant of niche specialization. SQRT and MMRT models predicted a higher optimum temperature for AOA-dominated PAO and NO fluxes compared with those of AOB. Additionally, PAO was dominated by AOA in acidic conditions, whereas both AOA- and AOB-dominated NO fluxes decreased with increasing pH. Consequently, net NO fluxes (AOA and AOB) under acidic conditions were approximately one to three-fold higher than those observed in alkaline conditions. Moreover, structural equation and linear regression modeling confirmed a significant positive correlation (R = 0.45, p < 0.01) between PAO and NO fluxes. Collectively, these results show the influence of ammonia oxidizer responses to temperature and pH on nitrification-driven NO fluxes, highlighting the potential for mitigating NO emissions via pH manipulation.
了解氨氧化古菌（AOA）和细菌（AOB）的环境生态位分异及其对硝化和氧化亚氮（NO）产生的相对贡献的影响，对于预测生态系统内的 NO 动态至关重要。在这里，我们使用氨氧化特异性抑制剂来测量 AOA 和 AOB 在 pH（4.0-9.0）和温度（10-45°C）梯度下对潜在氨氧化（PAO）和 NO 通量的差异贡献，共涉及 5 种土壤和 3 种湿地沉积物。使用 PTIO（2-苯基-4,4,5,5-四甲基咪唑啉-1-氧-3-氧化物）、1-辛炔和乙炔来区分 AOA 和 AOB 的活性。我们使用平方根生长（SQRT）和大分子速率理论（MMRT）模型来估计 AOA 和 AOB 主导的 PAO 和 NO 通量的特征温度和热力学特性。我们发现 AOA 和 AOB 在 PAO 方面占据不同的生态位，土壤温度是生态位特化的主要决定因素。SQRT 和 MMRT 模型预测 AOA 主导的 PAO 和 NO 通量的最适温度高于 AOB 主导的 PAO 和 NO 通量的最适温度。此外，在酸性条件下，PAO 主要由 AOA 主导，而 AOA 和 AOB 主导的 NO 通量都随着 pH 的增加而降低。因此，在酸性条件下，净 NO 通量（AOA 和 AOB）比在碱性条件下观测到的通量大约高 1 到 3 倍。此外，结构方程和线性回归模型证实了 PAO 和 NO 通量之间存在显著的正相关关系（R=0.45，p<0.01）。总的来说，这些结果表明氨氧化菌对温度和 pH 的响应会影响硝化驱动的 NO 通量，这凸显了通过 pH 控制来减少 NO 排放的潜力。
