Taylor Anne E, Mellbye Brett L
Department of Crop and Soil Science, Oregon State University, Corvallis, OR, United States.
Department of Microbiology, Oregon State University, Corvallis, OR, United States.
Front Microbiol. 2022 May 10;13:817986. doi: 10.3389/fmicb.2022.817986. eCollection 2022.
Microbially mediated nitrification plays an important role in the nitrogen (N) cycle, and rates of activity have been shown to change significantly with temperature. Despite this, the substrate affinities of nitrifying bacteria and archaea have not been comprehensively measured and are often assumed to be static in mathematical models of environmental systems. In this study, we measured the oxidation kinetics of ammonia- (NH) oxidizing archaea (AOA), NH-oxidizing bacteria (AOB), and two distinct groups of nitrite (NO )-oxidizing bacteria (NOB), of the genera and , by measuring the maximum rates of apparent activity ( ), the apparent half-saturation constant ( ), and the overall catalytic efficiency ( / ) over a range of temperatures. Changes in and with temperature were different between groups, with and catalytic efficiency increasing with temperature in AOA, while , , and catalytic efficiency increased in AOB. In NOB, and increased, but catalytic efficiency decreased significantly with temperature. NOB were variable, but increased while catalytic efficiency and remained relatively unchanged. Michaelis-Menten (MM) and Haldane (H) kinetic models of NH oxidation and NO oxidation based on the collected data correctly predict nitrification potential in some soil incubation experiments, but not others. Despite previous observations of coupled nitrification in many natural systems, our results demonstrate significant differences in response to temperature strategies between the different groups of nitrifiers; and indicate the need to further investigate the response of nitrifiers to environmental changes.
微生物介导的硝化作用在氮循环中起着重要作用，且已表明其活性速率会随温度显著变化。尽管如此，硝化细菌和古菌的底物亲和力尚未得到全面测定，并且在环境系统的数学模型中通常被假定为固定不变。在本研究中，我们通过测量一系列温度下的表观活性最大速率（ ）、表观半饱和常数（ ）和总体催化效率（ / ），测定了氨氧化古菌（AOA）、氨氧化细菌（AOB）以及两类不同的亚硝酸盐氧化细菌（NOB）（分别属于 和 属）的氧化动力学。不同组之间 和 随温度的变化有所不同，AOA中 和催化效率随温度升高，而AOB中 、 和催化效率升高。在 类NOB中， 和 升高，但催化效率随温度显著降低。 类NOB情况各异，但 升高，而催化效率和 相对保持不变。基于收集的数据建立的氨氧化和亚硝酸盐氧化的米氏（MM）和霍尔丹（H）动力学模型在一些土壤培养实验中能正确预测硝化潜力，但在其他实验中则不然。尽管此前在许多自然系统中观察到耦合硝化作用，但我们的结果表明不同硝化菌群在温度响应策略上存在显著差异；并表明需要进一步研究硝化菌对环境变化的响应。
