Perexilibacter aurantiacus gen. nov., sp. nov., a novel member of the family ‘Flammeovirgaceae’ isolated from sediment Jaewoo Yoon, 1 Shu Ishikawa, 2 Hiroaki Kasai 2 and Akira Yokota 1 Correspondence Jaewoo Yoon aa57058@mail.ecc.u-tokyo.ac.jp 1 Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-Ku, Tokyo 113-0032, Japan 2 Marine Biotechnology Institute Co. Ltd, 3-75-1, Heita, Kamaishi, Iwate 026-0001, Japan A strictly aerobic, Gram-negative, gliding, dull-orange-pigmented, rod-shaped bacterium, designated strain Shu-F-UV2-2 T , was isolated from sediment (Carp Island, Republic of Palau) and was the focus of a polyphasic taxonomic study. Phylogenetic analyses based on the 16S rRNA gene sequence revealed that the novel isolate was affiliated to the family ‘Flammeovirgaceae’ of the phylum Bacteroidetes and that it showed highest sequence similarity (85.5 %) to Flammeovirga yaeyamensis NBRC 100898 T . The novel isolate could be differentiated phenotypically and physiologically from recognized members of the family ‘Flammeovirgaceae’. The G+C content of the DNA was 43.0 mol%, MK-7 was the major menaquinone and iso-C 15 : 0 ,C 16 : 1 v7c and C 16 : 1 v5c were the major fatty acids. On the basis of this polyphasic evidence, it was concluded that strain Shu-F-UV2-2 T represents a novel species in a new genus of the family ‘Flammeovirgaceae’, for which the name Perexilibacter aurantiacus gen. nov., sp. nov. is proposed. The type strain is Shu-F-UV2-2 T (=MBIC06993 T =IAM 15413 T =KCTC 12867 T ). The Cytophaga–Flavobacterium–Bacteroides (CFB) group is also known as the phylum Bacteroidetes (Ludwig & Klenk, 2001). Molecular phylogenetic studies based on 16S rRNA gene sequence analysis have revealed that members of the phylum Bacteroidetes are ubiquitous in aquatic environ- ments (DeLong et al., 1993; Bowman et al., 1997; Glo ¨ckner et al., 1999; Cottrell & Kirchman, 2000; O’Sullivan et al., 2002). They play a significant role in the decomposition of organic matter and in carbon cycling within the global ecosystem (Cottrell & Kirchman, 2000; Nedashkovskaya et al., 2003). However, despite the significance of their ecological niche, the majority of members of this phylo- genetic group remain unknown and as yet uncultured (O’Sullivan et al., 2004). At the time of writing, genera such as Flammeovirga, Flexithrix, Persicobacter and Thermonema (Lewin, 1970; Hudson et al., 1989; Nakagawa et al., 1997; Takahashi et al., 2006) are incorporated within the family ‘Flammeovirgaceae’. Strain Shu-F-UV2-2 T was isolated from a sandy sediment, collected in August 2003 at a shallow beach 1 m deep on Carp Island, Republic of Palau (7u 5.259 N 134u 16.759 E). Surface sediment plus seawater from the same locality were collected by using a spatula. They were kept in a 15 ml tube for 5 h at 15 u C. For microbiological analyses, 1 g sediment was suspended in 15 ml autoclaved artificial seawater (Lyman & Fleming, 1940). A 50 ml sample of this suspension was applied to marine agar 2216 (Difco) and UV-irradiated for 2 min in a laminar flow cabinet. Dull-orange-coloured colonies appeared after incubation at 25 uC. We investigated the phylogenetic position of strain Shu-F-UV2-2 T by using a polyphasic taxonomic approach, including 16S rRNA gene sequence analysis, fatty acid composition analysis, quinone analysis and genotypic and physiological comparisons. Based on these data, it is proposed that the new isolate represents a novel species in a new genus of the family ‘Flammeovirgaceae’ in the phylum Bacteroidetes. The temperature and pH range for growth were determined by incubating on ten-fold diluted marine agar 2216 (MA). Salt tolerance was tested on R2A agar (Difco) with artificial seawater containing 0–5 % (w/v) NaCl. Gram staining was performed as described by Murray et al. (1994). Cell morphology was observed by using light microscopy (BX60; Olympus) and transmission electron microscopy (TEM). Gliding motility was determined as described by Perry (1973). For the TEM observations, cells were mounted on Formvar-coated copper grids and negatively stained with 1 % (w/v) aqueous uranyl acetate. Grids were observed in a JEOL 1010 transmission electron microscope (JEOL) operated at 100 kV. In the course of TEM, cells of various sizes were observed. Cells were mostly straight and rod- shaped. Cells varied between 0.3 and 0.5 mm in width and 10 Abbreviation: TEM, transmission electron microscopy. The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain Shu-F-UV2-2 T is AB276355. 964 64845 G 2007 IUMS Printed in Great Britain International Journal of Systematic and Evolutionary Microbiology (2007), 57, 964–968 DOI 10.1099/ijs.0.64845-0