Rufibacter radiotolerans sp. nov., a novel gamma-radiation-resistant bacterium isolated from rice field.

A red-pigmented isolate, designated DG31DT, was isolated from the soil of a rice field in South Korea. Cells were strictly aerobic, short rod-shaped, Gram-negative, oxidase-positive, and catalase-positive. The major polar lipid was phosphatidylethanolamine (PE), and the predominant respiratory quinone was MK-7. DG31DT showed high resistance to both the UV and gamma radiations. Based on the 16S rRNA gene sequence, strain DG31DT was related to Rufibacter immobilis MCC P1T (97.1%) and Rufibacter tibetensis 1351T (96.5%). The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between the strain DG31DT and the related Rufibacter sp. were between 74.1-77.6% and 19.9-21.9%, respectively. Strain DG31DT grew between 15 and 30 °C (optimum, 25 °C), at pH 6.0-8.0 (optimum, pH 7.0) and tolerated up to 1.0% NaCl (w/v). The major cellular fatty acids of the novel strain were summed feature 3 (C16:1 ω7c/C16:1 ω6c) and C16:1 ω5c. Flexirubin-type pigments were absent. On the basis of the phenotypic, phylogenetic, and chemotaxonomic data, strain DG31DT represents a novel species of the genus Rufibacter, for which the name Rufibacter radiotolerans sp. nov. is proposed. The type strain is DG31DT (= JCM 19446T = KCTC 32454T).