Functional Classification of Uncultured "Candidatus Caldiarchaeum subterraneum" Using the Maple System

• Published in: PloS one Vol. 10; no. 7; p. e0132994
• Main Authors: Takami, Hideto, Arai, Wataru, Takemoto, Kazuhiro, Uchiyama, Ikuo, Taniguchi, Takeaki
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 21.07.2015; Public Library of Science (PLoS)
• Subjects: Acids; Amino acids; Ammonia - chemistry; Analysis; Archaea; Archaea - classification; Archaea - genetics; Archaea - physiology; Bacteria; Bacteria - genetics; Bacteria - metabolism; Branched chain amino acids; Candidate species; Candidatus Caldiarchaeum subterraneum; Carbohydrate metabolism; Carbohydrates; Carbohydrates - chemistry; Carbon Cycle; Carbon fixation; Chain branching; Cladistic analysis; Classification; Classification systems; Cluster Analysis; Clustering; Computational Biology - methods; Databases, Genetic; Earth science; Encyclopedias; Enzymes; Eukaryotes; Genes; Genomes; Genomics; Glucose metabolism; Glycolysis; Glyoxylate cycle; Metabolism; Methods; Microorganisms; Modules; Nitrification; Nitrogen; Oxidation; Phenotype; Phylogenetics; Phylogeny; Physiological aspects; Physiology; Principal Component Analysis; Principal components analysis; Proteins; Pyruvic acid; Species; Species classification; Species Specificity; Sugar; Thermophilic bacteria; Thermophilic microorganisms; Tricarboxylic acid cycle
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0132994

In this study, the metabolic and physiological potential evaluator system based on Kyoto Encyclopedia of Genes and Genomes (KEGG) functional modules was employed to establish a functional classification of archaeal species and to determine the comprehensive functions (functionome) of the previously uncultivated thermophile "Candidatus Caldiarchaeum subterraneum" (Ca. C. subterraneum). A phylogenetic analysis based on the concatenated sequences of proteins common among 142 archaea and 2 bacteria, and among 137 archaea and 13 unicellular eukaryotes suggested that Ca. C. subterraneum is closely related to thaumarchaeotic species. Consistent with the results of the phylogenetic analysis, clustering and principal component analyses based on the completion ratio patterns for all KEGG modules in 79 archaeal species suggested that the overall metabolic and physiological potential of Ca. C. subterraneum is similar to that of thaumarchaeotic species. However, Ca. C. subterraneum possessed almost no genes in the modules required for nitrification and the hydroxypropionate-hydroxybutyrate cycle for carbon fixation, unlike thaumarchaeotic species. However, it possessed all genes in the modules required for central carbohydrate metabolism, such as glycolysis, pyruvate oxidation, the tricarboxylic acid (TCA) cycle, and the glyoxylate cycle, as well as multiple sets of sugar and branched chain amino acid ABC transporters. These metabolic and physiological features appear to support the predominantly aerobic character of Ca. C. subterraneum, which lives in a subsurface thermophilic microbial mat community with a heterotrophic lifestyle.