Abstract An unresolved question in microbial ecology is whether the available ammonium concentration has a differential impact on the growth of newly discovered complete ammonia-oxidizing bacteria (CAOB) and their counterparts, the well-known ammonia-oxidizing bacteria (AOB) and archaea (AOA). To address this issue, soil microcosms were cultured for 40 days with ammonium concentrations of 0, 5, 50, 200, and 500 μg NH+ 4-N g−1 soil. Quantitative PCR analysis suggested that AOB grew in response to the two highest ammonium concentrations, whereas CAOB only grew significantly at native and low ammonium concentrations, demonstrating an AOA-like niche specialization favoring oligotrophic environments but being tolerant to a broader ammonium concentration than AOA. Moreover, phylogenetic and Pearson correlation analysis indicated that species from clade B rather than clade A of CAOB contributed to the nitrification process. This study highlights an important role of the local ammonium concentration in affecting the ecological niche differentiation of comammox and canonical ammonia-oxidizing prokaryotes.

中文翻译：

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铵浓度决定了 comammox 和典型氨氧化原核生物在土壤微观世界中的差异生长

摘要 微生物生态学中一个悬而未决的问题是可用铵浓度是否对新发现的完全氨氧化细菌 (CAOB) 及其对应物、众所周知的氨氧化细菌 (AOB) 和古细菌 (AOA) 的生长有不同的影响。 ）。为了解决这个问题，在铵浓度为 0、5、50、200 和 500 μg NH+ 4-N g−1 土壤的情况下，将土壤微观世界培养了 40 天。定量 PCR 分析表明，AOB 响应两个最高的铵浓度而生长，而 CAOB 仅在天然和低铵浓度下显着生长，表明类似 AOA 的生态位有利于贫营养环境，但比 AOA 能耐受更广泛的铵浓度。而且，系统发育和 Pearson 相关性分析表明，来自 CAOB 的进化枝 B 而不是进化枝 A 的物种对硝化过程有贡献。这项研究强调了局部铵浓度在影响 comammox 和经典氨氧化原核生物的生态位分化方面的重要作用。