Anaerobic ammoniumoxidation (anammox) is the mainmicrobial N loss pathway in alpine wetland soils of the Qinghai-Tibet Plateau

Anaerobic ammonium oxidation (anammox) is an important process in the biogeochemical cycle of nitrogen (N). However, knowledge remains limited on the anammox bacterial community, controlling factors, anammox rates and contributions to N loss in alpine wetland ecosystems with low-temperatures and deficient oxygen concentrations. This study focused on the distribution, abundance and biodiversity of anammox bacteria and their contribution to N-2 production in the rhizosphere and bulk soils of alpine wetlands from the Qinghai-Tibet Plateau along an altitude gradient and discussed their potential relationship with environmental variables. A high diversity of anammox bacteria was found in alpine wetland soils, with most of the detected anammox bacteria classified as unknown species. The anammox bacterial abundance based on the 16S rRNA gene ranged from 1.35 x 10(3) to 2.52 x 10(4) copies.g(-1) in all the samples, and the anammox process generally contributed 62.66%-88.77% of the N-2 production in rhizosphere and bulk soils among the sites at different altitudes, except for the summer bulk soil in Jiuzhi (30.52%) and Maduo (28.84%). The anammox bacterial community was closely linked to the NO2- concentration and water content, while the abundance and activity of anammox bacteria showed a significantly positive correlation with the NO3- concentrations and denitrification rates in both bulk and rhizosphere soils (p < 0.05). These results emphasized the key role of anammox in N cycling in the high-altitude alpine wetlands of Qinghai-Tibet, and extended our understanding of the community dynamics of anammox bacteria and their environmental importance. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the distribution, abundance, and biodiversity of anammox bacteria in alpine wetlands on the Qinghai-Tibet Plateau, showing their key role in nitrogen cycling and close relationship with environmental variables. The results highlighted the importance of anammox bacteria in high-altitude alpine wetlands and expanded our understanding of their community dynamics and environmental significance.