Isolation of 'Candidatus Nitrosocosmicus franklandus', a novel ureolytic soil archaeal ammonia oxidiser with tolerance to high ammonia concentration

Laura E. Lehtovirta-Morley, Jenna Ross, Linda Hink, Eva B. Weber, Cécile Gubry-Rangin, Cécile Thion, James I. Prosser, Graeme W. Nicol

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Studies of the distribution of ammonia oxidising archaea (AOA) and bacteria (AOB) suggest distinct ecological niches characterised by ammonia concentration and pH, arising through differences in substrate affinity and ammonia tolerance. AOA form five distinct phylogenetic clades, one of which, the 'Nitrososphaera sister cluster', has no cultivated isolate. A representative of this cluster, named 'Candidatus Nitrosocosmicus franklandus', was isolated from a pH 7.5 arable soil and we propose a new cluster name: 'Nitrosocosmicus'. While phylogenetic analysis of amoA genes indicates its association with the Nitrososphaera sister cluster, analysis of 16S rRNA genes provided no support for a relative branching that is consistent with a 'sister cluster', indicating placement within a lineage of the order Nitrososphaerales. 'Ca. N. franklandus' is capable of ureolytic growth and its tolerances to nitrite and ammonia are higher than in other AOA and similar to those of typical soil AOB. Similarity of other growth characteristics of 'Ca. N. franklandus' with those of typical soil AOB isolates reduces support for niche differentiation between soil AOA and AOB and suggests that AOA have a wider physiological diversity than previously suspected. In particular, the high ammonia tolerance of 'Ca. N. franklandus' suggests potential contributions to nitrification in fertilised soils.

Original languageEnglish
Article numberfiw057
Pages (from-to)1-10
Number of pages10
JournalFEMS Microbiology Ecology
Issue number5
Early online date13 Mar 2016
Publication statusPublished - May 2016

Bibliographical note

The authors would like to thank Mr Kevin Mackenzie and Mrs Gillian Milne (University of Aberdeen) for technical support with scanning electron microscopy, and Dr Robin Walker for access to the Woodlands Field experimental plots at the SRUC,Craibstone Estate, Aberdeen.

This work was financially supported by Natural Environmental Research Council (standard grants NE/I027835/1 and NE/L006286/1 and fellowship NE/J019151/1), EC Marie Curie ITN NORA, Grant Agreement No. 316472, the AXA Research Fund and the Centre for Genome Enabled Biology and Medicine, University of Aberdeen.


  • thaumarchaeota
  • nitrososphaera sister cluster
  • soil
  • ammonia inhibition
  • nitrosocosmicus
  • nitrification


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