Pseudogracilibacillus Endophyticus Sp. Nov., a Moderately Thermophilic and Halophilic Species Isolated from Plant Root

A Gram-stain-positive strain, designated DT7-02, was isolated from the surface-sterilized root of Oenotherabiennis (evening primrose) and subjected to taxonomic characterization. Cells of DT7-02 were slender rod-shaped, motile by means of flagella, and oxidase- and catalase-positive. The colonies were circular, pinkish-yellow, opaque, glistering and 1-2 mm in diameter. The strain was moderately thermophilic and halophilic, as growth occurred at 20-44 °C (optimum 40 °C), pH 7-10 (optimum pH 8-9) and in the presence of 0-8 % of NaCl (optimum 4 %) in tryptic soy broth. The analysis of 16S rRNA gene sequences indicated that the strain represented a member of the genus Pseudogracilibacillus of the family Bacillaceae, and the sequence similarity was 96.5 % with Pseudogracilibacillus auburnensis P-207 and 95.9 % with Pseudogracilibacillus marinus NIOT-bflm-S4. Other related taxa were Ornithinibacillus contaminans DSM 22953 and Sinibacillus soli KCTC 33117, with 16S rRNA gene sequence similarities of 95.4 and 94.3 %, respectively. The major cellular fatty acids of DT7-02 were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The DNA G+C content was 35.1 mol%, and the respiratory quinone was MK-7. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol and phosphatidylethanolamine. The combination of chemotaxonomic properties enabled differentiation of DT7-02 from the other two species of the genus Pseudogracilibacillus. The results of phylogenetic, phenotypic and chemotaxonomic analyses demonstrate that strain DT7-02 (=KCTC 33854=JCM 31192) merits recognition as representing a novel species of the genus Pseudogracilibacillus, for which the name Pseudogracilibacillusendophyticus sp. nov. is proposed.