Spirosoma aureum sp. nov., and Hymenobacter russus sp. nov., radiation-resistant bacteria in Cytophagales order isolated from soil

A Gram-stain-negative, aerobic, nonmotile, yellow-colored strain BT328(T) and Gram-stain-negative, aerobic, non-motile, red-colored strain BT18(T) were isolated from the soil collected in Korea. Phylogenetic analyses based on 16S rRNA gene sequence revealed that strain BT328(T) formed a distinct lineage within the family Spirosomaceae (order Cytophagales, class Cytophagia) and was most closely related to a member of the genus Spirosoma, Spirosoma terrae 15J9-4(T) (95.9% 16S rRNA gene sequence similarity). Optimal growth occurred at 25 degrees C, pH 7.0 and in the absence of NaCl. The predominant cellular fatty acids were summed feature 3 (C-16:1 omega 6c/C-16:1 omega 7c) and C-16:1 omega 5c. The major respiratory quinone was MK-7. The major polar lipid was phosphatidylethanolamine. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain BT18(T) formed a distinct lineage within the family Hymenobacteraceae (order Cytophagales, class Cytophagia, phylum Bacteroidetes) and was most closely related to members of the genus Hymenobacter, Hymenobacter knuensis 16F7C-2(T) (97.0% 16S rRNA gene sequence similarity). Optimal growth occurred at 25 degrees C and pH 7.0 without NaCl. The major fatty acids were iso-C-15:0 and anteiso-C-15:0. The major menaquinone was MK-7. The major polar lipid was phosphatidylethanolamine. Biochemical, chemotaxonomic and phylogenetic analyses indicated that strains BT328(T) and BT18(T) represents a novel bacterial species within the genus Spirosoma and Hymenobacter, respectively. For which the name Spirosoma aureum and Hymenobacter russus is proposed. The type strain of S. aureum is BT328(T) (=KCTC 72365(T) = NBRC 114506(T)) and the type strain of H. russus is BT18(T) (=KCTC 62610(T) = NBRC 114380(T)).