title: Ammonia oxidation is not required for growth of Group 1.1c soil Thaumarchaeota.
abstract: Thaumarchaeota are among the most abundant organisms on Earth and are ubiquitous. Within this phylum, all cultivated representatives of Group 1.1a and Group 1.1b Thaumarchaeota are ammonia oxidizers, and play a key role in the nitrogen cycle. While Group 1.1c is phylogenetically closely related to the ammonia-oxidizing Thaumarchaeota and is abundant in acidic forest soils, nothing is known about its physiology or ecosystem function. The goal of this study was to perform in situ physiological characterization of Group 1.1c Thaumarchaeota by determining conditions that favour their growth in soil. Several acidic grassland, birch and pine tree forest soils were sampled and those with the highest Group 1.1c 16S rRNA gene abundance were incubated in microcosms to determine optimal growth temperature, ammonia oxidation and growth on several organic compounds. Growth of Group 1.1c Thaumarchaeota, assessed by qPCR of Group 1.1c 16S rRNA genes, occurred in soil, optimally at 30°C, but was not associated with ammonia oxidation and the functional gene amoA could not be detected. Growth was also stimulated by addition of organic nitrogen compounds (glutamate and casamino acids) but not when supplemented with organic carbon alone. This is the first evidence for non-ammonia oxidation associated growth of Thaumarchaeota in soil.
authors.affiliation: Institute of Biological and Environmental Sciences, Cruickshank Building, St Machar Drive, University of Aberdeen, Aberdeen, AB24 3UU, UK e.weber@abdn.ac.uk.
authors.forename: Eva B
authors.initials: EB
authors.lastname: Weber
authors.affiliation: Institute of Biological and Environmental Sciences, Cruickshank Building, St Machar Drive, University of Aberdeen, Aberdeen, AB24 3UU, UK.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Lehtovirta-Morley
authors.affiliation: Institute of Biological and Environmental Sciences, Cruickshank Building, St Machar Drive, University of Aberdeen, Aberdeen, AB24 3UU, UK.
authors.forename: James I
authors.initials: JI
authors.lastname: Prosser
authors.affiliation: Institute of Biological and Environmental Sciences, Cruickshank Building, St Machar Drive, University of Aberdeen, Aberdeen, AB24 3UU, UK.
authors.forename: Cécile
authors.initials: C
authors.lastname: Gubry-Rangin
mesh_terms: D000596:Amino Acids / Q000494:pharmacology; D000641:Ammonia / Q000378:metabolism*; D001105:Archaea / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D018698:Glutamic Acid / Q000494:pharmacology; D058458:Nitrogen Cycle; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012987:Soil; D012988:Soil Microbiology
chemical_list: D000596:Amino Acids; D012336:RNA, Ribosomal, 16S; D012987:Soil; C017721:casamino acids; D018698:Glutamic Acid; D000641:Ammonia
keywords: Thaumarchaeota; acidic forest; organic carbon; organic nitrogen; soil archaea; temperature