Mucilaginibacter aurantiaciroseus sp. nov. and Mucilaginibacter flavidus sp. nov., isolated from Renlongba glacier on the Tibetan Plateau

Abstract

Strains RB4R14T and RT5R15T, two Gram-stain-negative, aerobic, rod-shaped, non-motile bacteria, were isolated from ice and cryoconite of Renlongba glacier, respectively, on the Tibetan Plateau, PR China. The results of phylogenetic analysis based on 16S rRNA genes indicated that strains RB4R14T and RT5R15T belonged to the genus Mucilaginibacter with the highest similarities to Mucilaginibacter rigui WPCB133T (98.78 %) and Mucilaginibacter xinganensis BJC16-A31T (97.64 %), respectively. The genomic DNA G+C contents of strains RB4R14T and RT5R15T were 42.8 and 43.1 mol%, respectively. The digital DNA–DNA hybridization values between strains RB4R14T, RT5R15T and their close relatives were below 31.9 and 17.4 %, respectively. The average nucleotide identity values between the two novel strains and their close relatives were 79.5–82.0 and 77.9–79.3 % respectively, indicating the novelty of the two isolates at a species level. The two novel strains contained MK-7 as the major menaquinone, and summed feature 3 (comprising C16 : 1  ω7c and/or C16 : 1  ω6c), iso-C15 : 0 and iso-C17 : 0-3OH as the major fatty acids. The major polar lipid of the two novel strains were phosphatidylethanolamine. Based on phenotypic, chemotaxonomic and phylogenetic results, we propose two novel species, Mucilaginibacter aurantiaciroseus sp. nov. (RB4R14T=CGMCC 1.11911T=NBRC 114020T) and Mucilaginibacter flavidus sp. nov. (RT5R15T=CGMCC 1.23117T=NBRC 113930T).