title: Thermotoga profunda sp. nov. and Thermotoga caldifontis sp. nov., anaerobic thermophilic bacteria isolated from terrestrial hot springs.
abstract: Two thermophilic, strictly anaerobic, Gram-negative bacteria, designated strains AZM34c06(T) and AZM44c09(T), were isolated from terrestrial hot springs in Japan. The optimum growth conditions for strain AZM34c06(T) were 60 °C, pH 7.4 and 0% additional NaCl, and those for strain AZM44c09(T) were 70 °C, pH 7.4 and 0% additional NaCl. Complete genome sequencing was performed for both strains, revealing genome sizes of 2.19 Mbp (AZM34c06(T)) and 2.01 Mbp (AZM44c09(T)). Phylogenetic analyses based on 16S rRNA gene sequences and the concatenated predicted amino acid sequences of 33 ribosomal proteins showed that both strains belonged to the genus Thermotoga. The closest relatives of strains AZM34c06(T) and AZM44c09(T) were the type strains of Thermotoga lettingae (96.0% similarity based on the 16S rRNA gene and 84.1% similarity based on ribosomal proteins) and Thermotoga hypogea (98.6 and 92.7% similarity), respectively. Using blast, the average nucleotide identity was 70.4-70.5% when comparing strain AZM34c06(T) and T. lettingae TMO(T) and 76.6% when comparing strain AZM44c09(T) and T. hypogea NBRC 106472(T). Both values are far below the 95% threshold value for species delineation. In view of these data, we propose the inclusion of the two isolates in the genus Thermotoga within two novel species, Thermotoga profunda sp. nov. (type strain AZM34c06(T) = NBRC 106115(T) = DSM 23275(T)) and Thermotoga caldifontis sp. nov. (type strain AZM44c09(T) = NBRC 106116(T) = DSM 23272(T)).
authors.affiliation: NITE Biological Resource Center (NBRC), National Institute of Technology and Evaluation (NITE), 2-5-8 Kazusakamatari, Kisarazu, Chiba 292-0818, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Mori
authors.affiliation: NITE Biological Resource Center (NBRC), National Institute of Technology and Evaluation (NITE), 2-5-8 Kazusakamatari, Kisarazu, Chiba 292-0818, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamazoe
authors.affiliation: NITE Biological Resource Center (NBRC), National Institute of Technology and Evaluation (NITE), 2-5-8 Kazusakamatari, Kisarazu, Chiba 292-0818, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Hosoyama
authors.affiliation: NITE Biological Resource Center (NBRC), National Institute of Technology and Evaluation (NITE), 2-5-8 Kazusakamatari, Kisarazu, Chiba 292-0818, Japan.
authors.forename: Shoko
authors.initials: S
authors.lastname: Ohji
authors.affiliation: NITE Biological Resource Center (NBRC), National Institute of Technology and Evaluation (NITE), 2-5-8 Kazusakamatari, Kisarazu, Chiba 292-0818, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Fujita
authors.affiliation: Faculty of Science, Kyushu University, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Jun-Ichiro
authors.initials: JI
authors.lastname: Ishibashi
authors.affiliation: Department of Geosciences, Graduate School of Science, Shizuoka University, 836 Oya, Suruga-ku, Shizuoka 422-8529, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kimura
authors.affiliation: NITE Biological Resource Center (NBRC), National Institute of Technology and Evaluation (NITE), 2-5-8 Kazusakamatari, Kisarazu, Chiba 292-0818, Japan.
authors.forename: Ken-Ichiro
authors.initials: KI
authors.lastname: Suzuki
mesh_terms: D015373:Bacterial Typing Techniques; D001482:Base Composition; D004269:DNA, Bacterial / Q000235:genetics; D005227:Fatty Acids / Q000737:chemistry; D016965:Gram-Negative Anaerobic Straight, Curved, and Helical Rods / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D045482:Hot Springs / Q000382:microbiology*; D007564:Japan; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D005227:Fatty Acids; D012336:RNA, Ribosomal, 16S