International Program in Hazardous Substance and Environmental Management, Graduate School, Chulalongkorn University, Bangkok, Thailand.
Research Program in Hazardous Substance Management in Agricultural Industry, Center of Excellence on Hazardous Substance Management, Bangkok, Thailand.
Environ Sci Pollut Res Int. 2018 Mar;25(9):8676-8687. doi: 10.1007/s11356-017-1155-z. Epub 2018 Jan 10.
In this study, two laboratory nitrifying reactors (NRI and NRII), which were seeded by sludge from different sources and operated under different operating conditions, were found to possess distinct dominant ammonia-oxidizing microorganisms. Ammonia-oxidizing archaeal (AOA) amoA genes outnumbered ammonia-oxidizing bacterial (AOB) amoA genes in reactor NRI, while only AOB amoA genes were detectable in reactor NRII. The AOA amoA gene sequences retrieved from NRI were characterized within the Nitrososphaera sister cluster of the group 1.1b Thaumarchaeota. Two inhibitors for ammonia oxidation, allylthiourea (ATU) and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO), were applied individually and as a mixture to observe the ammonia-oxidizing activity of both microorganisms in the reactors' sludge. The results indicated that AOA and AOB jointly oxidized ammonia in NRI, while AOB played the main role in ammonia oxidation in NRII. DNA-stable isotope probing with labeled C-HCO was performed on NRI sludge. Incorporation of C into AOA and AOB implied that both microorganisms may perform autotrophy during ammonia oxidation. Taken together, the results from this study provide direct evidence demonstrating the contribution of AOA and AOB to ammonia oxidation in the nitrifying reactors.
在这项研究中，两个实验室硝化反应器（NRI 和 NRII），分别接种了来自不同来源的污泥，并在不同的操作条件下运行，被发现拥有明显不同的优势氨氧化微生物。在 NRI 中，氨氧化古菌（AOA）amoA 基因的数量超过了氨氧化细菌（AOB）amoA 基因，而在 NRII 中只能检测到 AOB amoA 基因。从 NRI 中回收的 AOA amoA 基因序列属于第 1.1b 组硝化螺旋菌的硝化球菌姐妹群。两种氨氧化抑制剂，烯丙基硫脲（ATU）和 2-苯基-4,4,5,5-四甲基咪唑啉-1-氧 3-氧化物（PTIO），分别单独和混合应用于观察反应器污泥中两种微生物的氨氧化活性。结果表明，AOA 和 AOB 共同氧化 NRI 中的氨，而 AOB 在 NRII 中的氨氧化中起主要作用。用标记的 C-HCO 对 NRI 污泥进行 DNA 稳定同位素探针法。C 掺入到 AOA 和 AOB 中表明，这两种微生物在氨氧化过程中可能都进行自养。总的来说，这项研究的结果提供了直接证据，证明了 AOA 和 AOB 对硝化反应器中氨氧化的贡献。
