Candidatus Nitrosocaldus cavascurensis, an Ammonia Oxidizing, Extremely Thermophilic Archaeon with a Highly Mobile Genome

Frontiers in Microbiology

Michael Melcher¹  Christa Schleper¹  Claudia Rossel¹  Kevin Pfeifer¹  Melina Kerou¹  Michaela Stieglmeier¹  Sophie S. Abby²  Mart Krupovic³ 

[1] Division of Archaea Biology and Ecogenomics, Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria;Laboratoire Techniques de l’Ingénierie Médicale et de la Complexité – Informatique, Mathématiques et Applications, Centre National de la Recherche Scientifique, Université Grenoble Alpes, Grenoble, France;Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Institut Pasteur, Paris, France;

关键词: ammonia oxidation;    archaea;    thaumarchaeota;    nitrification;    mobile genetic elements;    thermophilic adaptations;   

DOI  :  10.3389/fmicb.2018.00028

来源: DOAJ

【 摘 要 】

Ammonia oxidizing archaea (AOA) of the phylum Thaumarchaeota are widespread in moderate environments but their occurrence and activity has also been demonstrated in hot springs. Here we present the first enrichment of a thermophilic representative with a sequenced genome, which facilitates the search for adaptive strategies and for traits that shape the evolution of Thaumarchaeota. Candidatus Nitrosocaldus cavascurensis has been enriched from a hot spring in Ischia, Italy. It grows optimally at 68°C under chemolithoautotrophic conditions on ammonia or urea converting ammonia stoichiometrically into nitrite with a generation time of approximately 23 h. Phylogenetic analyses based on ribosomal proteins place the organism as a sister group to all known mesophilic AOA. The 1.58 Mb genome of Ca. N. cavascurensis harbors an amoAXCB gene cluster encoding ammonia monooxygenase and genes for a 3-hydroxypropionate/4-hydroxybutyrate pathway for autotrophic carbon fixation, but also genes that indicate potential alternative energy metabolisms. Although a bona fide gene for nitrite reductase is missing, the organism is sensitive to NO-scavenging, underlining the potential importance of this compound for AOA metabolism. Ca. N. cavascurensis is distinct from all other AOA in its gene repertoire for replication, cell division and repair. Its genome has an impressive array of mobile genetic elements and other recently acquired gene sets, including conjugative systems, a provirus, transposons and cell appendages. Some of these elements indicate recent exchange with the environment, whereas others seem to have been domesticated and might convey crucial metabolic traits.

【 授权许可】

Unknown