Five strains, NBRC 3271 T , NBRC 3272, NBRC 3263, NBRC 3260 and NBRC 3269 were examined genetically, phylogenetically, phenotypically and chemotaxonomically. The DNA G+C contents of the five strains were 55.1-56.4 mol%. The five strains had low levels of DNA-DNA hybridization of 13-51 % to the type strains of Gluconobacter frateurii, Gluconobacter thailandicus, Gluconobacter oxydans, Gluconobacter cerinus, Gluconobacter albidus and Gluconobacter kondonii and formed a cluster that was separate from the type strains of the six Gluconobacter species given above in phylogenetic trees based on 16S rRNA gene and 16S-23S rRNA gene internal transcribed spacer sequences. The five strains weakly produced dihydroxyacetone from glycerol, but not 2,5-diketo-D-gluconate or a water-soluble brown pigment from D-glucose and contained ubiquinone-10. The five strains were assigned as representing a novel species of the genus Gluconobacter, for which the name Gluconobacter japonicus sp. nov. is proposed. The type strain is NBRC 3271 T (5BCC 14458 T 5strain 7 T , K. Kondo). Cells of the type strain are motile by means of polar flagella and the DNA G+C content is 56.4 mol%.Members of the genus Gluconobacter are characterized physiologically as not being able to oxidize acetate and lactate and chemotaxonomically by having ubiquinone-10 (Q-10) as a major quinone (Asai, 1935;Asai et al., 1964;Yamada et al., 1969;Gosselé et al., 1983). The combination of the phenotypic and the chemotaxonomic characteristics has been used to classify a large number of isolated acetic acid bacteria as belonging to the genus Gluconobacter (Yamada et al., 1999;Tanaka et al., 1999;Huong et al., 2007).At the time of writing, the genus Gluconobacter contained seven species with validly published names: G. oxydans (the type species), G. cerinus, G. frateurii, G. asaii, G. albidus, G. thailandicus and G. kondonii (De Ley, 1961;Skerman et al., 1980;Gosselé et al., 1983; Yamada & Akita, 1984a, b;Mason & Claus, 1989;Yukphan et al., 2004cYukphan et al., , 2005Tanasupawat et al., 2004Tanasupawat et al., , 2005Malimas et al., 2007Malimas et al., , 2008. G. asaii is considered to be a later heterotypic synonym of G. cerinus (Katsura et al., 2002;Yamada et al., 1999;Tanaka et al., 1999).The heterogeneity of strains assigned to G. frateurii was recognized by Malimas et al. (2006), based on 16S-23S rRNA gene internal transcribed spacer (ITS) restriction and sequence analyses. In a restriction analysis of the 16S-23S rRNA gene ITS with six restriction endonucleases, the strains were largely divided into two groups, Group III and Group IV. However, Group III was further divided into Group III-1, Group III-2, Group III-3, Group III-4 and Group III-5. In a phylogenetic tree based on 16S-23S rRNA Extraction and isolation of bacterial chromosome DNA were performed by using a modification of the method of Marmur (1961) (Saito & Miura, 1963;Ezaki et al., 1983). The DNA base composition was determined by using the method of Tamaoka & Komagata (1984). The DNA G+C contents of strains...
