International Journal of Systematic and Evolutionary Microbiology (2002), 52, 1767–1772 DOI : 10.1099/ijs.0.02240-0 NOTE Halomonas halocynthiae sp. nov., isolated from the marine ascidian Halocynthia aurantium 1 Pacific Institute of Bioorganic Chemistry, Far- Eastern Branch, Russian Academy of Sciences, 690022 Vladivostok, Prospekt 100 Let Vladivostoku, 159, Russia 2 DSMZ – Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Mascheroder Weg 1b, D-38124 Braunschweig, Germany 3 GBF – Gesellschaft fu  r Biotechnologische Forschung GmbH, D-38124 Braunschweig, Germany L. A. Romanenko, 1 P. Schumann, 2 M. Rohde, 3 V. V. Mikhailov 1 and E. Stackebrandt 2 Author for correspondence : Erko Stackebrandt. Tel : 49 531 2616 352. Fax: 49 531 2616 418. e-mail : erkodsmz.de The marine bacterium strain KMM 1376 T was isolated from gill tissue of the ascidian Halocynthia aurantium, an inhabitant of the coastal waters of the Sea of Japan. Strain KMM 1376 T is an aerobic, Gram-negative, non-motile, encapsulated, non-pigmented, slightly halophilic bacterium that is characterized by fimbria-like structures, growth in 05–15 % NaCl at 7–35 C and absence of acid production from many carbohydrates. The DNA GMC content is 54 mol%. The main fatty acids are C 16:0 ,C 16:1 ω7c and C 18:1 ω9c. Comparative 16S rDNA sequence analysis of strain KMM 1376 T revealed 927–953 % sequence similarity to members of Halomonas. Based on phenotypic and phylogenetic characteristics, it is proposed that the novel isolate be classified as Halomonas halocynthiae sp. nov., with the type strain KMM 1376 T ( DSM 14573 T ). Keywords : Halomonas halocynthiae sp. nov., halophilic bacterium, marine environment, ascidian Halocynthia aurantium The genus Halomonas was described for aerobic, Gram-negative, halotolerant micro-organisms that are able to grow in a wide range of NaCl concentrations with a growth optimum of 8% (wv) NaCl (Vreeland et al., 1980). The genus Deleya (Baumann et al., 1983) has been described for aerobic, Gram-negative, mod- erately halophilic, rod-like bacteria isolated from the marine environment. Both genera were accommodated in the family Halomonadaceae (Franzmann et al., 1988). Subsequent investigations of Deleya, Halo- monas, Halovibrio and Volcaniella strains as well as Paracoccus halodenitrificans revealed that these taxa form a monophyletic group within the γ-Proteo- bacteria with corresponding chemotaxonomic and phenotypic properties and 16S rDNA similarity levels between 915 and 100 % (Dobson & Franzmann, 1996). Based on these results, species belonging to the four genera and P. halodenitrificans were combined in a single genus, Halomonas, of the emended family Halomonadaceae (Dobson & Franzmann, 1996). Not surprisingly, the descriptions of some of the species do ................................................................................................................................................. Published online ahead of print on 11 April 2002 as DOI 10.1099/ ijs.0.02240-0. Abbreviations : MA, Marine agar 2216; MB, Marine broth 2216; SWM, sea-water medium. The EMBL accession number for 16S rDNA sequence of strain KMM 1376 T is AJ417388. not match the emended genus description and the genus may be dissected into several genera in the future on the basis of additional phylogenetic and phenotypic evidence. At the time of writing, the genus Halomonas contains 22 species, including the recently described Halomonas campisalis, a denitrifying, moderately haloalkaliphilic bacterium (Mormile et al., 1999), Halomonas maga- diensis, an extremely halotolerant bacterium isolated from a soda lake of the East African Rift Valley (Duckworth et al., 2000), and Halomonas marisflavi,a halophilic bacterium from the Yellow Sea (Yoon et al., 2001). The tolerance of a broad range of salinity and the halophilic features of members of Halomonas allow these bacteria to inhabit any natural saline habitat. Halomonas species have been isolated from salterns, marine environments, estuarine waters, salt lakes and ponds, Antarctic saline lakes and saline soils (Vreeland et al., 1980 ; Baumann et al., 1983 ; Franzmann et al., 1987 ; Quesada et al., 1984, 1990 ; Valderrama et al., 1991 ; Mellado et al., 1995 ; Mormile et al., 1999; Duckworth et al., 2000 ; Bouchotroch et al., 2001). Strain KMM 1376 T (KMM ; Collection of Marine Micro-organisms, Pacific Institute of Bioorganic Chemistry, Vladivostok, Russia) was isolated from gill tissue of the ascidian Halocynthia aurantium, collected 02240  2002 IUMS Printed in Great Britain 1767