Al-Ajeel Sarah, Spasov Emilie, Sauder Laura A, McKnight Michelle M, Neufeld Josh D
Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
Water Res X. 2022 Mar 14;15:100131. doi: 10.1016/j.wroa.2022.100131. eCollection 2022 May 1.
Nitrification, the oxidation of ammonia to nitrate via nitrite, is important for many engineered water treatment systems. The sequential steps of this respiratory process are carried out by distinct microbial guilds, including ammonia-oxidizing bacteria (AOB) and archaea (AOA), nitrite-oxidizing bacteria (NOB), and newly discovered members of the genus that conduct complete ammonia oxidation (comammox). Even though all of these nitrifiers have been identified within water treatment systems, their relative contributions to nitrogen cycling are poorly understood. Although AOA contribute to nitrification in many wastewater treatment plants, they are generally outnumbered by AOB. In contrast, AOA and comammox typically dominate relatively low ammonia environments such as drinking water treatment, tertiary wastewater treatment systems, and aquaculture/aquarium filtration. Studies that focus on the abundance of ammonia oxidizers may misconstrue the actual role that distinct nitrifying guilds play in a system. Understanding which ammonia oxidizers are active is useful for further optimization of engineered systems that rely on nitrifiers for ammonia removal. This review highlights known distributions of AOA and comammox in engineered water treatment systems and suggests future research directions that will help assess their contributions to nitrification and identify factors that influence their distributions and activity.
硝化作用，即将氨通过亚硝酸盐氧化为硝酸盐的过程，对许多工程水处理系统而言至关重要。这一呼吸过程的连续步骤由不同的微生物群落执行，包括氨氧化细菌（AOB）和古菌（AOA）、亚硝酸盐氧化细菌（NOB），以及新发现的能够进行完全氨氧化（全程氨氧化菌）的属成员。尽管所有这些硝化菌已在水处理系统中被识别出来，但它们对氮循环的相对贡献却知之甚少。虽然AOA在许多污水处理厂的硝化作用中发挥作用，但它们的数量通常比AOB少。相比之下，AOA和全程氨氧化菌通常在氨含量相对较低的环境中占主导地位，如饮用水处理、三级污水处理系统以及水产养殖/水族馆过滤系统。专注于氨氧化菌丰度的研究可能会误解不同硝化群落在系统中实际发挥的作用。了解哪些氨氧化菌具有活性，对于进一步优化依赖硝化菌进行氨去除的工程系统很有帮助。本综述重点介绍了AOA和全程氨氧化菌在工程水处理系统中的已知分布情况，并提出了未来的研究方向，这将有助于评估它们对硝化作用的贡献，并确定影响它们分布和活性的因素。
