Ammonia-oxidizing archaea possess a wide range of cellular ammonia affinities

• Published in: The ISME Journal Vol. 16; no. 1; pp. 272 - 283
• Main Authors: Jung, Man-Young, Sedlacek, Christopher J., Kits, K. Dimitri, Mueller, Anna J., Rhee, Sung-Keun, Hink, Linda, Nicol, Graeme W., Bayer, Barbara, Lehtovirta-Morley, Laura, Wright, Chloe, de la Torre, Jose R., Herbold, Craig W., Pjevac, Petra, Daims, Holger, Wagner, Michael
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-01-2022; Nature Publishing Group
• Subjects: 14/34; 631/326/26/2527; 631/443/319; 704/158/855; Affinity; Ammonia; Ammonia - metabolism; Ammonia monooxygenase; Ammonia-oxidizing bacteria; Ammonium; Archaea; Archaea - genetics; Archaea - metabolism; Bacteria - genetics; Bacteria - metabolism; Biogeochemical cycles; Biomedical and Life Sciences; Cell surface; Ecology; Environmental Sciences; Evolutionary Biology; Guilds; Hypotheses; Life Sciences; Microbial Ecology; Microbial Genetics and Genomics; Microbiology; Nitrification; Nitrogen cycle; Oxidation; Oxidation-Reduction; Oxidizing agents; Phylogeny; Soil Microbiology; Substrate preferences; Substrates
• ISSN: 1751-7362; 1751-7370
• DOI: 10.1038/s41396-021-01064-z

Nitrification, the oxidation of ammonia to nitrate, is an essential process in the biogeochemical nitrogen cycle. The first step of nitrification, ammonia oxidation, is performed by three, often co-occurring guilds of chemolithoautotrophs: ammonia-oxidizing bacteria (AOB), archaea (AOA), and complete ammonia oxidizers (comammox). Substrate kinetics are considered to be a major niche-differentiating factor between these guilds, but few AOA strains have been kinetically characterized. Here, the ammonia oxidation kinetic properties of 12 AOA representing all major cultivated phylogenetic lineages were determined using microrespirometry. Members of the genus
Nitrosocosmicus
have the lowest affinity for both ammonia and total ammonium of any characterized AOA, and these values are similar to previously determined ammonia and total ammonium affinities of AOB. This contrasts previous assumptions that all AOA possess much higher substrate affinities than their comammox or AOB counterparts. The substrate affinity of ammonia oxidizers correlated with their cell surface area to volume ratios. In addition, kinetic measurements across a range of pH values supports the hypothesis that—like for AOB—ammonia and not ammonium is the substrate for the ammonia monooxygenase enzyme of AOA and comammox. Together, these data will facilitate predictions and interpretation of ammonia oxidizer community structures and provide a robust basis for establishing testable hypotheses on competition between AOB, AOA, and comammox.