Two thermophilic, strictly anaerobic, Gram-negative bacteria, designated strains AZM34c06T and AZM44c09T, were isolated from terrestrial hot springs in Japan. The optimum growth conditions for strain AZM34c06T were 60 °C, pH 7.4 and 0% additional NaCl, and those for strain AZM44c09T 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 (AZM34c06T) and 2.01 Mbp (AZM44c09T). 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 AZM34c06T and AZM44c09T 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 AZM34c06T and T. lettingae TMOT and 76.6% when comparing strain AZM44c09T and T. hypogea NBRC 106472T. 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 AZM34c06T = NBRC 106115T = DSM 23275T) and Thermotoga caldifontissp. nov. (type strain AZM44c09T = NBRC 106116T = DSM 23272T).
|Number of pages||9|
|Journal||International Journal of Systematic and Evolutionary Microbiology|
|Issue number||PART 6|
|Publication status||Published - Jun 2014|
All Science Journal Classification (ASJC) codes
- Ecology, Evolution, Behavior and Systematics