Low Temperature and Neutral pH Define “Candidatus Nitrotoga sp.” as a Competitive Nitrite Oxidizer in Coculture with Nitrospira defluvii
Low Temperature and Neutral pH Define “Candidatus Nitrotoga sp.” as a Competitive Nitrite Oxidizer in Coculture with Nitrospira defluvii
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DOI：
10.1128/aem.02569-18
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发表时间：
2019-03
影响因子：
4.4
通讯作者：
S. Wegen;Boris Nowka;E. Spieck
中科院分区：
文献类型：
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作者：
S. Wegen;Boris Nowka;E. Spieck
"Ca. Nitrotoga "是一种与环境高度相关的NOB，但只有少数代表存在生理数据。最初，它是在低温和低亚硝酸盐浓度的专门小生境中检测到的，但后来，它的无处不在的分布揭示了它在工程系统（如污水处理厂）中对氮去除的关键作用。在这项研究中，我们分析了Nitrotoga和Nitrospira在生物反应器中的竞争，并确定了K策略Ns的条件。defluvii几乎被Nitrotoga sp. BS所取代。我们表明，pH值是一个重要的因素，调节亚硝酸盐氧化富集的组合物与Nitrotoga属的优势。BS与NS。在7.4的中性pH与17 ° C的温度组合下进行defluvii。新的Nitrotoga文化的生理多样性提高了我们的知识生态位分化NOB功能硝化在次优条件下。摘要硝化作用是活性污泥脱氮的重要过程，可以避免氨氮和亚硝酸盐的毒害。除硝化螺菌外，"亚硝酸盐氧化菌"已被确定为在污水处理厂（WWTPs）中进行硝化的第二步（亚硝酸盐氧化为硝酸盐）的关键亚硝酸盐氧化细菌（NOB）。然而，Nitrotoga在某些植物中占主导地位的驱动力往往仍然不清楚，不能仅仅用温度效应来解释。在这项研究中，我们的特点的生理铵依赖Nitrotoga sp. BS与温度和pH值的变化，并评估其竞争力对Nitrospira defluvii。两种NOB均来自相同的污水处理厂，并且具有可比较的最佳pH值7.3。基于这些结果，在17 ° C或22 ° C下操作的分批反应器中进行与这些NOB的共培养实验，以比较它们在使用ImM亚硝酸盐的最佳（pH 7.4）或次佳（pH 6.4）条件下的丰度。如通过定量PCR（qPCR）、荧光原位杂交（FISH）和16S扩增子测序所揭示的，Nitrotoga sp. BS明显受到其最佳生长参数的青睐，并且优于Ns。在pH7.4和17 ° C下，defluvii，而6.4的pH对Ns更具选择性。第七节。我们的合成社区表明，生态位分化的NOB是由一个复杂的相互作用的环境参数的影响，并进行评估，为单一物种。重要性"Ca. Nitrotoga "是一种与环境高度相关的NOB，但只有少数代表存在生理数据。最初，它是在低温和低亚硝酸盐浓度的专门小生境中检测到的，但后来，它的无处不在的分布揭示了它在工程系统（如污水处理厂）中对氮去除的关键作用。在这项研究中，我们分析了Nitrotoga和Nitrospira在生物反应器中的竞争，并确定了K策略Ns的条件。defluvii几乎被Nitrotoga sp. BS所取代。我们表明，pH值是一个重要的因素，调节亚硝酸盐氧化富集的组合物与Nitrotoga属的优势。BS与NS。在7.4的中性pH与17 ° C的温度组合下进行defluvii。新的Nitrotoga文化的生理多样性提高了我们的知识生态位分化NOB功能硝化在次优条件下。
“Ca. Nitrotoga” is a NOB of high environmental relevance, but physiological data exist for only a few representatives. Initially, it was detected in specialized niches of low temperature and low nitrite concentrations, but later on, its ubiquitous distribution revealed its critical role for N removal in engineered systems like WWTPs. In this study, we analyzed the competition between Nitrotoga and Nitrospira in bioreactors and identified conditions where the K strategist Ns. defluvii was almost replaced by Nitrotoga sp. BS. We show that the pH value is an important factor that regulates the composition of the nitrite-oxidizing enrichment with a dominance of Nitrotoga sp. BS versus Ns. defluvii at a neutral pH of 7.4 in combination with a temperature of 17°C. The physiological diversity of novel Nitrotoga cultures improves our knowledge about niche differentiation of NOB with regard to functional nitrification under suboptimal conditions. ABSTRACT Nitrification is an essential process for N removal in activated sludge to avoid toxicity of ammonium and nitrite. Besides Nitrospira, “Candidatus Nitrotoga” has been identified as a key nitrite-oxidizing bacterium (NOB) performing the second step of nitrification, nitrite oxidation to nitrate, in wastewater treatment plants (WWTPs). However, the driving forces for the dominance of Nitrotoga in certain plants have often remained unclear and could not be explained solely by temperature effects. In this study, we characterized the physiology of the ammonium-dependent Nitrotoga sp. BS with regard to temperature and pH variations and evaluated its competitiveness against Nitrospira defluvii. Both NOB originated from the same WWTP and shared a comparable pH optimum of 7.3. Based on these results, coculturing experiments with these NOB were performed in batch reactors operated at either 17°C or 22°C to compare their abundances under optimal (pH 7.4) or suboptimal (pH 6.4) conditions using 1 mM nitrite. As revealed by quantitative PCR (qPCR), fluorescence in situ hybridization (FISH), and 16S amplicon sequencing, Nitrotoga sp. BS was clearly favored by its optimal growth parameters and dominated over Ns. defluvii at pH 7.4 and 17°C, whereas a pH of 6.4 was more selective for Ns. defluvii. Our synthetic communities revealed that niche differentiation of NOB is influenced by a complex interaction of environmental parameters and has to be evaluated for single species. IMPORTANCE “Ca. Nitrotoga” is a NOB of high environmental relevance, but physiological data exist for only a few representatives. Initially, it was detected in specialized niches of low temperature and low nitrite concentrations, but later on, its ubiquitous distribution revealed its critical role for N removal in engineered systems like WWTPs. In this study, we analyzed the competition between Nitrotoga and Nitrospira in bioreactors and identified conditions where the K strategist Ns. defluvii was almost replaced by Nitrotoga sp. BS. We show that the pH value is an important factor that regulates the composition of the nitrite-oxidizing enrichment with a dominance of Nitrotoga sp. BS versus Ns. defluvii at a neutral pH of 7.4 in combination with a temperature of 17°C. The physiological diversity of novel Nitrotoga cultures improves our knowledge about niche differentiation of NOB with regard to functional nitrification under suboptimal conditions.