Temperature differentially regulates estuarine microbial N2O production along a salinity gradient

Tie-Qiang Mao; Yong Zhang; Ya-Fei Ou; Xiao-Fei Li; Yan-Ling Zheng; Xia Liang; Min Liu; Li-Jun Hou; Hong-Po Dong

doi:10.1016/j.watres.2024.122454

Temperature differentially regulates estuarine microbial N₂O production along a salinity gradient

Water Res. 2024 Sep 15:267:122454. doi: 10.1016/j.watres.2024.122454. Online ahead of print.

Authors

Tie-Qiang Mao¹, Yong Zhang², Ya-Fei Ou¹, Xiao-Fei Li¹, Yan-Ling Zheng³, Xia Liang¹, Min Liu³, Li-Jun Hou⁴, Hong-Po Dong⁵

Affiliations

¹ State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China.
² College of Environmental and Resource Sciences, College of Carbon Neutral Modern Industry, Fujian Key Laboratory of Pollution Control and Resource Recycling, Fujian Normal University, Fuzhou 350117, China.
³ Key Laboratory of Geographic Information Science, Ministry of Education, East China Normal University, Shanghai 200241, China.
⁴ State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China. Electronic address: ljhou@sklec.ecnu.edu.cn.
⁵ State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China. Electronic address: hpdong@sklec.ecnu.edu.cn.

PMID: 39293343
DOI: 10.1016/j.watres.2024.122454

Abstract

Nitrous oxide (N₂O) is atmospheric trace gas that contributes to climate change and affects stratospheric and ground-level ozone concentrations. Ammonia oxidizers and denitrifiers contribute to N₂O emissions in estuarine waters. However, as an important climate factor, how temperature regulates microbial N₂O production in estuarine water remains unclear. Here, we have employed stable isotope labeling techniques to demonstrate that the N₂O production in estuarine waters exhibited differential thermal response patterns between nearshore and offshore regions. The optimal temperatures (T_opt) for N₂O production rates (N₂OR) were higher at nearshore than offshore sites. ¹⁵N-labeled nitrite (¹⁵NO₂^-) experiments revealed that at the nearshore sites dominated by ammonia-oxidizing bacteria (AOB), the thermal tolerance of ¹⁵N-N₂OR increases with increasing salinity, suggesting that N₂O production by AOB-driven nitrifier denitrification may be co-regulated by temperature and salinity. Metatranscriptomic and metagenomic analyses of enriched water samples revealed that the denitrification pathway of AOB is the primary source of N₂O, while clade II N₂O-reducers dominated N₂O consumption. Temperature regulated the expression patterns of nitrite reductase (nirK) and nitrous oxide reductase (nosZ) genes from different sources, thereby influencing N₂O emissions in the system. Our findings contribute to understanding the sources of N₂O in estuarine waters and their response to global warming.

Keywords: Aquatic microbes; Metatranscriptome; N(2)O production; Temperature; Yangtze River estuary.