Hymenobacter erythromyxa sp. nov., and Hymenobacter radioresistens sp. nov., Gamma and UV radiation resistant bacteria isolated from a Gamma ray irradiated soil

Abstract Two Gram-negative, gamma and UV tolerant bacterial strains, DG25AT and DG25BT, were isolated from soil samples exposed to 3kGy gamma radiation collected in Seoul, Korea. The cells grown on R2A agar at 25 °C were pink to red in colour. The phylogenetic analysis based on 16S rRNA gene sequence revealed that the strains belong to the genus Hymenobacter. The closest degrees of 16S rRNA gene sequence similarities to these strains, DG25AT and DG25BT, were found with Hymenobacter tibetensis NRRL B-51271T (96.5% and 96.6%, respectively). The multilocus sequence analysis (MLSA) tree based on the 14 housekeeping genes suggested that these two strains are distinct from other Hymenobacter species and represent novel candidates. The G+C contents of genomic DNA of DG25AT and DG25BT are 57.2 and 56.8 mol%, respectively. Chemotaxonomic data revealed that the strains contain iso-C15:0, anteiso-C15:0, C16:1 ω5c, summed feature3 (C16:1 ω7c/ C16:1 ω6c), and summed feature4 (anteiso B-C17:1 / iso I- C17:1) as the major fatty acids, and major polar lipid for both strains was phosphatidylethanolamine (PE). In addition, the strains showed resistance to gamma and UV radiation. Based on these data, each of strains DG25AT and DG25BT should be classified as a novel species, for which the names Hymenobacter erythromyxa sp. nov. (DG25AT =KCTC 32451T= JCM 19445T) and Hymenobacter radioresistens sp. nov., are proposed (DG25BT = KCTC 32452T = JCM 19444T).