| Title | Thermococcus indicus sp. nov., a Fe(III)-reducing hyperthermophilic archaeon isolated from the Onnuri Vent Field of the Central Indian Ocean ridge |
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| Author | Jae Kyu Lim1,2, Yun Jae Kim1,2, Jhung-Ahn Yang1, Teddy Namirimu1, Sung-Hyun Yang1, Mi-Jeong Park1,2, Yong Min Kwon3, Hyun Sook Lee1,2, Sung Gyun Kang1,2, Jung-Hyun Lee1,2, and Kae Kyoung Kwon1,2* |
| Address | 1Korea Institute of Ocean Science and Technology, Busan 49111, Republic of Korea, 2KIOST School, University of Science and Technology, Daejeon 34113, Republic of Korea, 3Department of Applied Research, National Marine Biodiversity Institute of Korea, Chungcheongnam-do 33662, Republic of Korea |
| Bibliography | Journal of Microbiology, 58(4),260-267, 2020, |
| DOI | 10.1007/s12275-020-9424-9 |
| Key Words | Thermococcus indicus sp. nov., Fe(III)-reduction, hyperthermophile, Indian Ocean, Onnuri Vent Field |
| Abstract | A strictly anaerobic, dissimilatory Fe(III)-reducing hyperthermophilic archaeon, designated as strain IOH1T, was isolated from a new deep-sea hydrothermal vent (Onnuri Vent Field) area in the Central Indian Ocean ridge. Strain IOH1T showed > 99% 16S rRNA gene sequence similarity with Thermococcus celericrescens TS2T (99.4%) and T. siculi DSM 12349T (99.2%). Additional three species T. barossii SHCK-94T (99.0%), T. celer Vu13T (98.8%), and T. piezophilus (98.6%) showed > 98.6% of 16S rRNA gene sequence similarity, however, the maximum OrthoANI value is 89.8% for the genome of T. celericrescens TS2T. Strain IOH1T cells are coccoid, 1.2–1.8 μm in diameter, and motile by flagella. Growth was at 70–82°C (optimum 80°C), pH 5.4–8.0 (optimum pH 6.0) with 2–4% (optimum 3%) NaCl. Growth of strain IOH1T was enhanced by starch, pyruvate, D(+)-maltose and maltodextrin as a carbon sources, and elemental sulfur as an electron acceptor; clearly different from those of related species T. celecrescens DSM 17994T and T. siculi DSM 12349T. Strain IOH1T, T. celercrescence DSM 17994T, and T. siculi DSM 12349T reduced soluble Fe(III)-citrate present in the medium, whereas the amount of total cellular proteins increased with the concomitant accumulation of Fe(II). We determined a circular chromosome of 2,234 kb with an extra-chromosomal archaeal plasmid, pTI1, of 7.7 kb and predicted 2,425 genes. The DNA G + C content was 54.9 mol%. Based on physiological properties, phylogenetic, and genome analysis, we proposed that strain IOH1T (= KCTC 15844T = JCM 39077T) is assigned to a new species in the genus Thermococcus and named Thermococcus indicus sp. nov. |