Microbes and nitrogen cycling
Nitrogen is an essential nutrient for all living organisms, and often the limiting factor for primary production and crop yield in natural and man-managed ecosystems. Nitrogen is transformed through different oxidation and reduction processes by microorganisms. Several of these processes directly or indirectly produce N2O, which is of particular interest for land management strategies, as it is a potent greenhouse gas.
Fig. 1. The Ultuna experimental site is our model system for studying how long-term changes in soil properties affect the ecology of soil microbial communities involved in N and soil organic matter cycling.
Within this UMC project, the ecology of ammonia-oxidizing and denitrifying prokaryotes, mainly in soil and sediments, is addressed (Fig. 1.). The significance of archaea in denitrification and N-cycling is also studied, as well as the evolution of the denitrification pathway. The ability to denitrify is sporadically distributed within clades, and closely related bacteria may have completely different denitrifying abilities. This, coupled with the potential occurrence of horizontal transfer of functional denitrification genes between distantly related species, and other evolutionary events, adds in new levels of complexity to the open question of the ecological significance of functional gene diversity (Fig. 2).
Fig. 2. Geostatistical modeling of the spatial distribution of denitrifying communities targeted by a set of functional gene markers at Logården experimental farm (data from a collaborative project with one of UMC's stakeholders).
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