title: Thermococcus coalescens sp. nov., a cell-fusing hyperthermophilic archaeon from Suiyo Seamount.
abstract: A cell-fusing hyperthermophilic archaeon was isolated from hydrothermal fluid obtained from Suiyo Seamount of the Izu-Bonin Arc. The isolate, TS1(T), is an irregular coccus, usually 0.5-2 microm 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 microm 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 degrees 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 degrees C, pH 5.2-8.7 and at NaCl concentrations of 1.5-4.5 %, with the optima being 87 degrees 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 TS1(T) and phylogenetically related Thermococcus species. We propose that isolate TS1(T) represents a novel species, Thermococcus coalescens sp. nov., with the name reflecting the cell fusion activity observed in the strain. The type strain is TS1(T) (=JCM 12540T=DSM 16538T).
authors.affiliation: Master's Program in Biosystem Studies, University of Tsukuba, Tsukuba 305-8572, Japan.|Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Kuwabara
authors.affiliation: Master's Program in Biosystem Studies, University of Tsukuba, Tsukuba 305-8572, Japan.
authors.forename: Masaomi
authors.initials: M
authors.lastname: Minaba
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Iwayama
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Inouye
authors.affiliation: Institute for Marine Resources and Environment, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8567, Japan.
authors.forename: Miwako
authors.initials: M
authors.lastname: Nakashima
authors.affiliation: Institute for Marine Resources and Environment, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8567, Japan.
authors.forename: Katsumi
authors.initials: K
authors.lastname: Marumo
authors.affiliation: Research Institute of Biological Resources, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8566, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Maruyama
authors.affiliation: Division of Chemistry, Center for Natural Science, Kitasato University, Sagamihara 228-8555, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Sugai
authors.affiliation: Division of Chemistry, Center for Natural Science, Kitasato University, Sagamihara 228-8555, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Itoh
authors.affiliation: Department of Earth and Planetary Science, Faculty of Science, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Jun-Ichiro
authors.initials: JI
authors.lastname: Ishibashi
authors.affiliation: Department of Earth & Planetary Science, The University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Urabe
authors.affiliation: Noda Institute for Scientific Research, Noda 278-0037, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kamekura
mesh_terms: D001482:Base Composition; D019641:DNA, Archaeal / Q000032:analysis / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D012623:Seawater / Q000382:microbiology; D013696:Temperature; D019712:Thermococcus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000648:ultrastructure
chemical_list: D019641:DNA, Archaeal; D004275:DNA, Ribosomal