International Journal of Systematic and Evolutionary Microbiology (2002), 52, 1831–1835 DOI : 10.1099/ijs.0.02156-0 NOTE Halomicrobium mukohataei gen. nov., comb. nov., and emended description of Halomicrobium mukohataei 1 Division of Microbial and Molecular Ecology, The Institute of Life Sciences, and The Moshe Shilo Minerva Center for Marine Biogeochemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel 2 Division of Biochemistry, Department of Chemistry, Faculty of Science and Arts, Marmara University, 81040 Istanbul, Turkey 3 Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-86023, Japan 4 Centre for Gene Research, Nagoya University, Chikusa-ku, Furo-cho 464- 8602, Japan 5 Dipartimento di Fisiologia Generale ed Ambientale, Universita ’ di Bari, Via Amendola 165/a, 70126 Bari, Italy Aharon Oren, 1 Rahel Elevi, 2 Satoshi Watanabe, 3 Kunio Ihara 4 and Angela Corcelli 5 Author for correspondence : Aharon Oren. Tel : ›972 2 6584951. Fax : ›972 2 6528008. e-mail : orena!shum.cc.huji.ac.il Haloarcula mukohataei, previously isolated from soils of salt flats in Argentina, was originally placed in the genus Haloarcula on the basis of 16S rRNA gene sequence comparison. However, its morphology and polar lipid composition differs from that of the other Haloarcula species. In addition, its phylogenetic distance from other Haloarcula species is rather large, and the 16S rDNA sequence does not contain many of the signature bases characteristic of the genus. Transfer of the species to a new genus was therefore recommended by the International Committee on Systematic Bacteriology Subcommittee on the taxonomy of Halobacteriaceae. A full description of the isolate, proposed as a member of a new genus, Halomicrobium, as Halomicrobium mukohataei comb. nov., is presented. The type strain is strain arg-2 T (fl JCM 9738 T fl DSM 12286 T fl ATCC 700874 T fl NCIMB 13541 T ). Keywords : Halomicrobium gen. nov., Haloarcula mukohataei, Halomicrobium mukohataei comb. nov., halophilic, archaea Haloarcula mukohataei was isolated by Ihara et al. (1997) from soils of salt flats in Argentina. It was placed in the genus Haloarcula on the basis of the similarity of its 16S rRNA gene sequence to the 16S rRNA sequences of the other species of the genus. In addition, its retinal proton pump, designated cruxrho- dopsin-2, is most similar in amino acid sequence to the proton pumps of Haloarcula argentinensis and Halo- arcula vallismortis (Sugiyama et al., 1994). However, it has been pointed out that there are a number of important properties in which Haloarcula mukohataei differs from the other representatives of the genus. It lacks TGD-2, the glycolipid found in all other Halo- arcula species, but contains a different (unidentified) glycolipid instead. Moreover, the similarity of its 16S rDNA with the 16S rRNA genes of the other Halo- arcula species is rather low (89–1–90–5 % similarity only, compared to & 94–1% among the other Halo- ................................................................................................................................................. This paper is dedicated to the memory of Takeshi Tamura (deceased 15 October 1991), who originally described Haloarcula mukohataei. Published online ahead of print on 7 June 2002 as DOI 10.1099/ ijs.0.02156-0. The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain arg-2 T (fl JCM 9738 T fl DSM 12286 T fl ATCC 700874 T fl NCIMB 13541 T ) is D50850. arcula species) and there is a mean similarity of 86–4% between Haloarcula mukohataei and members of the other genera of the Halobacteriaceae. In addition, the 16S rDNA sequence does not contain many of the signature bases characteristic of the genus (Grant et al., 2001). For these reasons, the International Com- mittee on Systematic Bacteriology Subcommittee on the taxonomy of Halobacteriaceae has suggested that transfer of Haloarcula mukohataei to a new genus may be justified (Oren & Ventosa, 2000 ; see also Ventosa, 2001). Here, we formally propose the transfer of Haloarcula mukohataei to a new genus, i.e. Halomicrobium gen. nov., as Halomicrobium mukohataei comb. nov. We also present an emended description of the species in accordance with the requirements of the minimal standards for the description of new taxa in the order Halobacteriales (Oren et al., 1997). Haloarcula mukohataei (JCM 9738 T , purchased from the Japan Collection of Microorganisms) was grown in medium (designated medium no. 1) of the following composition (g l -"): NaCl, 200; KCl, 2; MgSO % \ 7H # O, 2 ; trisodium-citrate, 3 ; Tris, 5 ; yeast extract, 1; Casamino acids, 5. The pH was adjusted to 7–2 with HCl. For solid media, agar was added to a con- 02156 # 2002 IUMS Printed in Great Britain 1831