Gluconobacter japonicus sp. nov., an acetic acid bacterium in the Alphaproteobacteria Taweesak Malimas, 1 Pattaraporn Yukphan, 1 Mai Takahashi, 2 Yuki Muramatsu, 2 Mika Kaneyasu, 2 Wanchern Potacharoen, 1 Somboon Tanasupawat, 3 Yasuyoshi Nakagawa, 2 Morakot Tanticharoen 1 and Yuzo Yamada 1 3 Correspondence Yuzo Yamada yamada333@kch.biglobe.ne.jp 1 BIOTEC Culture Collection (BCC), National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathumthani 12120, Thailand 2 Biological Resource Center (NBRC), Department of Biotechnology, National Institute of Technology and Evaluation (NITE), Kisarazu 292-0818, Japan 3 Department of Microbiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand 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; Gossele ´ 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; Gossele ´ et al., 1983; Yamada & Akita, 1984a, b; Mason & Claus, 1989; Yukphan et al., 2004c, 2005; Tanasupawat et al., 2004, 2005; Malimas et al., 2007, 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 Abbreviation: ITS, internal transcribed spacer. 3JICA Senior Overseas Volunteer, Japan International Cooperation Agency (JICA), Shibuya-ku, Tokyo 151-8558, Japan; Professor Emeritus, Shizuoka University, Shizuoka 422-8529, Japan. The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequences of strains NBRC 3271 T , NBRC 3260, NBRC 3263, NBRC 3272 and NBRC 3269 are AB253435, AB178400, AB253434, AB253436 and AB178408, respectively. A table showing DNA–DNA hybridization values for strains NBRC 3271 T , NBRC 3260, NBRC 3263, NBRC 3272 and NBRC 3269 and the type strains of other species of Gluconobacter and Acetobacter aceti is available as supplementary material with the online version of this paper. International Journal of Systematic and Evolutionary Microbiology (2009), 59, 466–471 DOI 10.1099/ijs.0.65740-0 466 65740 G 2009 IUMS Printed in Great Britain