Effect of Temperature and Oxygen on Ammonia Oxidiser Communities and Nitrification in Cryoturbated Arctic Soils

Ricardo Jorge Eloy Alves, Stefanie Aiglsdorfer, Maria Mooshammer, Jörg Schnecker, Birgit Wild, Jiri Barta, Katerina Diakova, Petr Capek, Iva Kohoutova, Tim Urich, Norman Gentsch, Antje Gittel, Georg Guggenberger, Nikolay Lashchinskiy, Robert Mikuta, Olga Shibistova, Andreas Richter, Hana Santruckova, Christa Schleper

Arctic soils contain large amounts of organic carbon and nitrogen (N), which are expected to undergo increased decomposition and mineralisation under current environmental changes, such as higher temperatures. Although N is the main limiting nutrient in Arctic soils, we lack knowledge about relationships between N transformations and their microbial catalysers in response to environmental changes in these ecosystems. For instance, ammonia-oxidising archaea (AOA) and bacteria (AOB) perform the rate-limiting step in nitrification, which regulates inorganic N availability through oxidation of ammonium (NH4+) to nitrate via nitrite, and are known to be affected by NH4+, temperature and oxygen conditions.
We investigated population dynamics of AOA and AOB, their role in nitrification and dependence on N mineralisation in three Arctic tundra soil horizons incubated for 19 weeks under different temperature and oxygen regimes. AOA and AOB were analysed by quantification and high-throughput sequencing of genes encoding subunit A of the enzyme ammonia monooxygenase, and gross N transformations were determined by 15N pool dilution. We show that higher temperatures stimulate nitrification more than N mineralisation aerobically, in association with higher ammonia oxidiser abundance. Preliminary results indicated changes in ammonia oxidiser communities, namely of AOA, suggesting that environmental selection of distinct functional clades may underlie differences in nitrification activity.

Department für Ökogenomik und Systembiologie
Externe Organisation(en)
Gottfried Wilhelm Leibniz Universität Hannover, University of South Bohemia in České Budějovice , Carl von Ossietzky Universität Oldenburg, Austrian Polar Research Institute (APRI), University of Bergen (UiB), Aarhus University, Russian Academy of Sciences
ÖFOS 2012
Mikrobiologie, Ökosystemforschung
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