Abstract

Denitrification causes nitrogen losses from terrestrial ecosystems. The magnitude of nitrogen loss depends on the prevalence of denitrifiers, which show ecological differences if they harbour nirS or nirK genes encoding nitrite reductases with the same biological function. Thus, it is relevant to understand the mechanisms of co-existence of denitrifiers, including their response to environmental filters and competition due to niche similarities. We propose a framework to analyse the co-existence of denitrifiers across multiple assemblages by using nir gene-based co-occurrence networks. We applied it in Mediterranean soils before and during 1 year after an experimental fire. Burning did not modify nir community structure, but significantly impacted co-occurrence patterns. Bacteria with the same nir co-occurred in space, and those with different nir excluded each other, reflecting niche requirements: nirS abundance responded to nitrate and salinity, whereas nirK to iron content. Prior to fire, mutual exclusion between bacteria with the same nir suggested competition due to niche similarities. Burning provoked an immediate rise in mineral nitrogen and erased the signals of competition, which emerged again within days as nir abundances peaked. nir co-occurrence patterns can help infer the assembly mechanisms of denitrifying communities, which control nitrogen losses in the face of ecological disturbance.

Published in

Environmental Microbiology
2021, Volume: 23, number: 1, pages: 239-251
Publisher: WILEY

SLU Authors

• Hallin, Sara

  • Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Microbiology
Environmental Sciences


Publication identifier

DOI: https://doi.org/10.1111/1462-2920.15298

Permanent link to this page (URI)

https://res.slu.se/id/publ/109250