Thermodynamic response of ammonia-oxidizing archaea and bacteria in vegetable soils across Yangtze River Basin

Ammonia-oxidizing archaea (AOA) and bacteria (AOB) are key drivers of nitrous oxide (N₂O) production. Understanding their thermodynamic response parameters is critical for developing effective N₂O mitigation strategies under global warming scenarios. However, the thermodynamic response parameters of AOA and AOB in relation to potential ammonia oxidation (PAO) rates and N₂O production remain poorly understood. This study evaluates the contributions of AOA and AOB to nitrite (NO₂⁻) and N₂O production in representative greenhouse vegetable soils of the Yangtze River Basin utilizing combined inhibitor approaches. The thermodynamic responses of AOA and AOB were assessed across a temperature gradient of 5–45 °C using the square root growth (SQRT) and macromolecular rate theory (MMRT) models. Results revealed that N₂O production was closely linked to PAO rates, which varied significantly (0.91 to 25.98 μg g⁻¹ d⁻¹) among soil types. The theoretical temperature ranges for AOA and AOB were −7.67 to 56.94 °C and −7.06 to 54.40 °C, respectively. AOA demonstrated a significantly higher optimal activity temperature (T_opt) than AOB, with differences of 6.05 ± 2.33 °C (SQRT) and 6.72 ± 2.34 °C (MMRT). Furthermore, AOA exhibited greater temperature sensitivity (T_{s_max}) compared to AOB. In conclusion, AOA demonstrates higher activity in high-temperature environments and greater sensitivity to temperature fluctuations, indicating a more pronounced response to N₂O emissions under global warming.