Pedosphere 29(1): 24--33, 2019
ISSN 1002-0160/CN 32-1315/P
©2019 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Chronic Nitrogen Fertilization Modulates Competitive Interactions Among Microbial Ammonia Oxidizers in a Loess Soil
DONG Xingchen1,2, ZHANG Jian1,2, QIU Huizhen1,2, ZHANG He1,2, LUO Chaoyue1,2, DENG Delei1,2, SHEN Qirong3, JIA Zhongjun4
1College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou 730070(China);
2Gansu Provincial Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou 730070(China);
3College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095(China);
4State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008(China)
      Nitrogen (N) application may lead to niche segregation of soil ammonia-oxidizing archaea (AOA) and bacteria (AOB), thereby reducing the competitive interactions between AOA and AOB due to higher ammonium substrate availability. However, the adaptive mechanisms of AOA and AOB under N enrichment remain poorly understood. Stable isotope probing (SIP) microcosm incubation was employed to reveal community changes of active AOA and AOB in a loess soil from a field experiment growing potatoes that received no N (control, CK), low N (LN, 75 kg N ha-1), and high N (HN, 375 kg N ha-1). The results showed that the soil potential nitrification rate (PNR) was measured by culturing of the soil samples from the field experiment. Soil PNR was significantly increased in HN by 87.5% and 67.5% compared with CK and LN, respectively. Compared with CK, the 13C-amoA genes of soil AOA and AOB in HN had 2.58×104 and 1.55×106 copies, representing 1.6-and 16.2-fold increase respectively. It was indicated that AOB dominated soil ammonia oxidation. A phylogenetic analysis of the 13C-amoA gene showed that N application significantly increased the proportion of 54d9-like AOA up to 90% in HN, while the Nitrososphaera gargensis-like and Nitrososphaera viennensis-like AOA were inhibited and completely disappeared. Nitrogen application also resulted in the community shift of active AOB-dominant group from Nitrosospira briensis-like to Nitrosospira sp. TCH711-like. Our study provides compelling evidence for the emergence and maintenance of active nitrifying communities under the intensified N input to an agricultural ecosystem.
Key Words:  ammonia monooxygenase,ammonia-oxidizing archaea,ammonia-oxidizing bacteria,chronic nitrogen application,microbial community,potential nitrification rate,stable isotope probing
Citation: Dong X C, Zhang J, Qiu H Z, Zhang H, Luo C Y, Deng D L, Shen Q R, Jia Z J. 2019. Chronic nitrogen fertilization modulates competitive interactions among microbial ammonia oxidizers in a loess soil. Pedosphere. 29(1):24-33.
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