Phylogenetic diversity and UV resistance analysis of radiation-resistant bacteria isolated from the water in Han River

Spirosoma rhododendri sp. nov., isolated from a flower of royal azalea (Rhododendron schlippenbachii)

A Gram-negative, non-motile, strictly aerobic and rod- or filamentous-shaped strain, CJU-R4T, was isolated from a flower of royal azalea (Rhododendron schlippenbachii) collected in the Republic of Korea. Strain CJU-R4T was catalase-positive and oxidase-negative, and grew at 15–33 °C (optimum, 28–20 °C), at pH 5.0–8.0 (optimum, pH 7.0–8.0), and in the presence of 0–1 % NaCl (w/v; optimum, 0 %). Strain CJU-R4T had the highest 16S rRNA gene sequence similarity to Spirosoma oryzae RHs22T (96.6 %), revealing less than 93 % sequence similarity to other type strains. Phylogenetic and phylogenomic analysis also revealed strain CJU-R4T formed a robust cluster with S. oryzae RHs22T. The major fatty acids were summed feature 3 (comprising C16 : 1  ω7c and/or C16 : 1  ω6c; 33.0 %), C16 : 1  ω5c (22.1 %), iso-C15 : 0 (12.6 %) and C16 : 0 (10.7 %). The polar lipids were composed of phosphatidylethanolamine, three unidentified aminophospholipids, one unidentified phospholipid and four unidentified lipids. Menaquinone-7 was detected as the sole respiratory quinone. The genomic DNA G+C content was 55.2 mol%. The average nucleotide identity and digital DNA–DNA hybridization values between strain CJU-R4T and Spirosoma oryzae DSM 28354T were 81.5 and 23.9 %, respectively. Based on the results of the phenotypic and genotypic analyses, strain CJU-R4T is considered to represent a novel species of the genus Spirosoma , for which the name Spirosoma rhododendri sp. nov. is proposed. The type strain is CJU-R4T (=KACC 21264T=NBRC 114513T).

Adhaeribacter radiodurans sp. nov., isolated from the rhizospheric soil of Elymus tsukushiensis, a plant native to the Dokdo Islands, Republic of Korea

KUDC8001^T was isolated from the rhizosperic soil of Elymus tsukushiensis in the Dokdo Islands, Republic of Korea. Strain KUDC8001^T was Gram-stain-negative, non-motile and rod-shaped. KUDC8001^T was catalase- and oxidase-positive. This strain is capable of growing at 4-37 °C and pH 7.0-8.0 and exhibited optimal growth at 25 °C and pH 7.0. It could be grown in R2A, nutrient agar and ISP2 agar plates. The cell width ranged from 0.7 to 1.0 µm, and length ranged from 2.5 to 5.5 µm. The genomic G+C content was 40.8 mol%. Phylogenetic analysis, based on 16S rRNA gene sequences, revealed that the strain KUDC8001^T belongs to the genus Adhaeribacter, which is most closely related to the strain A. pallidiroseus HMF7616^T (97.5%). The DNA relatedness of KUDC8001^T with the type strains of A. pallidiroseus HMF7616^T, A. swui 17 mud1-7^T and A. arboris HMF7605^T was ≤80.3 % based on average nucleotide identity calculations and ≤86.9 % based on average amino acid identity calculations. In silico DNA-DNA hybridization values of the strain KUDC8001^T with the most closely related strains were 22.1, 24.0 and 24.4 %. Based on its phenotypic, phylogenetic, genetic and chemotaxonomic features, the strain KUDC8001^T should be considered as a novel species in the genus Adhaeribacter, for which we have proposed the name Adhaeribacter radiodurans sp. nov. The type strain is KUDC8001^T (=KCTC 82078^T=CGMCC 1.18475^T).