Life on N2O: deciphering the ecophysiology of N2O respiring bacterial communities in a continuous culture

M. Conthe Calvo, Lea Wittorf, J. Gijs Kuenen, Robbert Kleerebezem, Mark C.M. van Loosdrecht, Sara Hallin*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

37 Citations (Scopus)
68 Downloads (Pure)

Abstract

Reduction of the greenhouse gas N2O to N2 is a trait among denitrifying and non-denitrifying microorganisms having an N2O reductase, encoded by nosZ. The nosZ phylogeny has two major clades, I and II, and physiological differences among organisms within the clades may affect N2O emissions from ecosystems. To increase our understanding of the ecophysiology of N2O reducers, we determined the thermodynamic growth efficiency of N2O reduction and the selection of N2O reducers under N2O- or acetate-limiting conditions in a continuous culture enriched from a natural community with N2O as electron acceptor and acetate as electron donor. The biomass yields were higher during N2O limitation, irrespective of dilution rate and community composition. The former was corroborated in a continuous culture of Pseudomonas stutzeri and was potentially due to cytotoxic effects of surplus N2O. Denitrifiers were favored over non-denitrifying N2O reducers under all conditions and Proteobacteria harboring clade I nosZ dominated. The abundance of nosZ clade II increased when allowing for lower growth rates, but bacteria with nosZ clade I had a higher affinity for N2O, as defined by μmax/Ks. Thus, the specific growth rate is likely a key factor determining the composition of communities living on N2O respiration under growth-limited conditions.

Original languageEnglish
Pages (from-to)1-12
JournalThe ISME Journal: multidisciplinary journal of microbial ecology
Volume12
DOIs
Publication statusPublished - 7 Feb 2018

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