Thermococcus coalescens sp. nov., a cell-fusing hyperthermophilic archaeon from Suiyo Seamount

Tomohiko Kuwabara, Masaomi Minaba, Yukihiro Iwayama, Isao Inouye, Miwako Nakashima, Katsumi Marumo, Akihiko Maruyama, Akihiko Sugai, Toshihiro Itoh, Jun Ichiro Ishibashi, Tetsuro Urabe, Masahiro Kamekura

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Abstract

A cell-fusing hyperthermophilic archaeon was isolated from hydrothermal fluid obtained from Suiyo Seamount of the Izu-Bonin Arc. The isolate, TS1T, is an irregular coccus, usually 0.5-2 μm in diameter and motile with a polar tuft of flagella. Cells in the exponential phase of growth fused at room temperature in the presence of DNA-intercalating dye to become as large as 5 μm in diameter. Fused cells showed dark spots that moved along in the cytoplasm. Large cells with a similar appearance were also observed upon culture at 87 °C, suggesting the occurrence of similar cell fusions during growth. Transmission electron microscopy revealed that cells in the exponential phase possessed a thin and electron-lucent cell envelope that could be lost subsequently during culture. The fragile cell envelope must be related to cell fusion. The cells grew at 57-90 °C, pH 5.2-8.7 and at NaCl concentrations of 1.5-4.5%, with the optima being 87 °C, pH 6.5 and 2.5% NaCl. The isolate was an anaerobic chemo-organotroph that grew on either yeast extract or tryptone as the sole growth substrate. The genomic DNA G+C content was 53.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequencing indicated that the isolate was closely related to Thermococcus species. However, no significant DNA-DNA hybridization was observed between genomic DNA of strain TS1T and phylogenetically related Thermococcus species. We propose that isolate TS1T represents a novel species, Thermococcus coalescens sp. nov., with the name reflecting the cell fusion activity observed in the strain. The type strain is TS1T (= JCM 12540T = DSM 16538T).

Original languageEnglish
Article number63432
Pages (from-to)2507-2514
Number of pages8
JournalInternational Journal of Systematic and Evolutionary Microbiology
Volume55
Issue number6
DOIs
Publication statusPublished - Nov 1 2005

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All Science Journal Classification (ASJC) codes

  • Microbiology
  • Ecology, Evolution, Behavior and Systematics

Cite this

Kuwabara, T., Minaba, M., Iwayama, Y., Inouye, I., Nakashima, M., Marumo, K., ... Kamekura, M. (2005). Thermococcus coalescens sp. nov., a cell-fusing hyperthermophilic archaeon from Suiyo Seamount. International Journal of Systematic and Evolutionary Microbiology, 55(6), 2507-2514. [63432]. https://doi.org/10.1099/ijs.0.63432-0