Exogenous nitrogen input skews estimates of microbial nitrogen use efficiency by ecoenzymatic stoichiometry

作     者：Lifei Sun Daryl L.Moorhead Yongxing Cui Wolfgang Wanek Shuailin Li Chao Wang 

作者机构：CAS Key Laboratory of Forest Ecology and Management Institute of Applied Ecology Chinese Academy of Sciences Department of Environmental Sciences University of Toledo Sino-French Institute for Earth System Science College of Urban and Environmental Sciences Peking University Division of Terrestrial Ecosystem Research Center of Microbiology and Environmental Systems Science University of Vienna 

出 版 物：《Ecological Processes》 (生态过程(英文))

年 卷 期：2023年

页      面：625-631页

核心收录：

学科分类：0710[理学-生物学] 1007[医学-药学(可授医学、理学学位)] 100705[医学-微生物与生化药学] 07[理学] 071005[理学-微生物学] 10[医学] 

基　　金：funded by the National Key Research and Development Program of China (2020YFA0608100) the National Natural Science Foundation of China (32001174 and 32101378) the Major Program of Institute of Applied Ecology,Chinese Academy of Sciences (IAEMP202201) Key Research Program of Frontier Sciences,Chinese Academy of Sciences (ZDBS-LY-DQC019) Project funded by China Postdoctoral Science Foundation (2022M710004) 

摘      要：Background Ecoenzymatic stoichiometry models（EEST） are often used to evaluate microbial nutrient use efficiency,but the validity of these models under exogenous nitrogen（N） input has never been clarified. Here, we investigated the effects of long-term N addition（as urea） on microbial N use efficiency（NUE）, compared EEST and18O-labeling methods for determining NUE, and evaluated EEST s theoretical assumption that the ratios of standard ecoenzymatic activities balance resource availability with microbial *** We found that NUE estimated by EEST ranged from 0.94 to 0.98. In contrast, estimates of NUE by the18O-labeling method ranged from 0.07 to 0.30. The large differences in NUE values estimated by the two methods may be because the sum of β-N-acetylglucosaminidase and leucine aminopeptidase activities in the EEST model was not limited to microbial N acquisition under exogenous N inputs, resulting in an overestimation of microbial NUE by EEST. In addition, the acquisition of carbon by N-acquiring enzymes also likely interferes with the evaluation of NUE by *** Our results demonstrate that caution must be exercised when using EEST to evaluate NUE under exogenous N inputs that may skew standard enzyme assays.