Temperature affects the kinetics of nitrite oxidation and nitrification coupling in four agricultural soils. (September 2019)

• Record Type: Journal Article
• Authors: Taylor, Anne E.; Myrold, David D.; Bottomley, Peter J.
• Is Part Of: Soil biology and biochemistry. Volume 136(2019)
• Publication Date: 2019-09
• Subjects: Nitrite oxidizing bacteria -- Thermodynamic characteristics -- Substrate affinity -- Nitrite accumulation; Soil biochemistry -- Periodicals; Soil biology -- Periodicals; Sols -- Biochimie -- Périodiques; Sols -- Biologie -- Périodiques; Sols -- Microbiologie -- Périodiques; Bodembiologie; Biochemie; 631.46
• DOI: 10.1016/j.soilbio.2019.107523
• Languages: English
• ISSNs: 0038-0717

Abstract

Abstract: The oxidation of ammonia (NH3 ) to nitrite (NO2 − ) by archaea and bacteria (AOA and AOB) in soil has been studied intensively for >140 y. However, relatively little attention has been focused on the activity of nitrite oxidizing bacteria (NOB), which catalyze the oxidation of NO2 −, despite ample published evidence of soil NO2 − accumulation, and the temperature dependent accumulation of NO2 − in wastewater and aquatic environments. This study evaluated the response of NO2 − oxidizing activity to temperature in four Oregon agricultural soils. Rates of NO2 − oxidizing potentials (NOP) were measured at 4–42 °C in all soils. Evaluation of the thermodynamic parameters found that the NOB have a similar temperature range and optimal temperature as the NH3 oxidizer response observed in Taylor et al. (2016). A determination of kinetic parameters of NO2 − oxidation at 17, 30, and 37 °C found a trend for the apparent maximum velocity (Vmax ) to be greater at 30 than 17 °C, and significant, soil-specific changes in substrate affinity (Km ) of NO2 − consumption. Although the potential rates of NO2 − oxidation exceeded those of NH3 oxidation, NO2 − accumulated under at least one temperature in all soils. There were only weak correlations between NO2 − accumulation and rates of NH3 or NO2 − oxidation, the abundance of Nitrobacter nxr A or Nitrospira nxr B genes or the total ( nxr A + nxr B)/ amo A gene ratio. The apparent Km did not correlate with NO2 − accumulation at any temperature; however, utilizing the obtained Vmax and Km we found that Michaelis-Menten kinetics predict that an accumulation of measurable NO2 − is required to drive equal rates of NH3 and NO2 − oxidation. Implications of reductions in NO2 − affinity by NOB at some temperatures that result in increased NO2 − accumulation in soils include plant toxicity and the loss of soil N through increased production of reactive N-oxide gases. Graphical abstract: Soil nitrite oxidizing bacteria (NOB) have similar temperature range and optimal temperature as the ammonia (NH3 ) oxidizing archaea and bacteria (AOA and AOB). A determination of kinetic parameters of NO2 − oxidation at 17, 30, and 37 °C found a trend for the apparent maximum velocity (Vmax ) to be greater at 30 than 17 °C, and significant changes in substrate affinity (Km ) of NO2 − consumption. Utilizing the obtained Vmax and Km we found that Michaelis-Menten kinetics predict that an accumulation of measurable NO2 − is required to drive equal rates of NH3 and NO2 − oxidation. Image 1 Highlights: NO2 − oxidizing activity was measured at 4–42 °C in Oregon agricultural soils. NH3 and NO2 − oxidizing bacteria share similar temperature ranges. Substrate affinity (Km ) of NO2 − consumption changed in response to temperature. NO2 − accumulation is required to drive coupled nitrification at some temperatures.