Exploring microbial N2O reduction: a continuous enrichment in nitrogen free medium

Monica Conthe*, J. Gijs Kuenen, Robbert Kleerebezem, Mark C.M. van Loosdrecht

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)


N2O is a potent greenhouse gas, but also a potent electron acceptor. In search of thermodynamically favourable – yet undescribed – metabolic pathways involving N2O reduction, we set up a continuous microbial enrichment, inoculated with activated sludge, fed with N2O as the sole electron acceptor and acetate as an electron donor. A nitrogen-free mineral medium was used with the intention of creating a selective pressure towards organisms that would use N2O directly as source of nitrogen for cell synthesis. Instead, we obtained a culture dominated by microorganisms of the Rhodocyclaceae family growing by N2O reduction to N2 coupled to N2 fixation. Biomass yields of this culture were 40% lower than those of a previously reported culture grown under comparable conditions but with an NH+ 4 -amended medium, as expected from the extra energy expense of N2 fixation. Interestingly, we found no significant difference in yields whether N2O or acetate was the growth-limiting substrate in the chemostat in contrast to the study with NH+ 4-amended medium, in which biomass yields were roughly 30% lower during acetate limiting conditions.

Original languageEnglish
Pages (from-to)102-107
Number of pages6
JournalEnvironmental Microbiology Reports
Issue number1
Publication statusPublished - 1 Feb 2018


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