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Three novel Shewanella species are described on the basis of phenotypic, chemotaxonomic and phylogenetic studies. A total of six novel halophilic, aerobic organisms with the ability to produce eicosapentaenoic acid (EPA) were isolated from various sea animals in Japan. Cells of all six isolates were Gram-negative, rod-shaped and motile by means of polar flagella. They were able to produce large amounts of EPA (about 20 % of the total fatty acids) and had isoprenoid quinones Q-7 and Q-8 as major components. Analysis of the nearly complete 16S rRNA gene sequences of the novel isolates showed that they are very close phylogenetically (sequence similarity >99 %) and the closest species was Shewanella pealeana, with 97 % sequence similarity. However, analysis of gyrB sequences indicated that the novel isolates were divided into three groups at sufficient phylogenetic distance to indicate that they are different species (<90 % sequence similarity). DNA–DNA hybridization experiments supported this conclusion. The first group (three strains) had positive reactions for lipase, DNase, ONPG and trimethylamine oxide (TMAO) reduction and had G+C contents of 43 mol% (determined by HPLC). The second group (two strains) was positive for urease, DNase, ONPG and TMAO reduction but not lipase. Their G+C content was 45 mol%. The third group (one strain) was negative for ONPG, DNase and TMAO reduction and had a G+C content of 43 mol%. Strains of the second group, but not those of the first or third groups, grew at 32 °C. On the basis of the polyphasic taxonomic data, the novel strains isolated from intestines of sea animals are placed in three novel species of the genus Shewanella: Shewanella marinintestina sp. nov. (type strain: JCM 11558T=LMG 21403T), Shewanella schlegeliana sp. nov. (type strain: JCM 11561T=LMG 21406T) and Shewanella sairae sp. nov. (type strain: JCM 11563T=LMG 21408T).
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