The genus Flavobacterium belongs to the family Flavobacteriaceae and its members are widely distributed in the environment. Taxonomic descriptions of strains LS1R47T and LS1R49T isolated from the Laigu glacier on the Tibetan Plateau, China, are presented in this study. Both strains were psychrotolerant, Gram-stain-negative, aerobic and rod-shaped. The comparative analysis of 16S rRNA gene sequences showed that strain LS1R47T was closest to Flavobacterium bizetiae CIP 105534T (98.90 %) and strain LS1R49T was closest to Flavobacterium collinsii 983-08T (98.73 %). The 16S rRNA gene sequence similarity, average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two novel isolates were 99.4, 86.0 and 30.9 %, respectively. The ANI and dDDH values between strains LS1R47T and LS1R49T and their closely relatives were below 87.6 and 33.3 %, respectively. Phylogenomic analysis showed that the two strains cluster together with Flavobacterium hydatis ATCC 29551T. Both strains contained MK-6 as sole quinone, phosphatidylethanolamine as the principal polar lipid, and summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1 ω7c), iso-C15 : 0 3-OH, C15 : 0 3-OH and iso-C17 : 0 3-OH as the main fatty acids. These results indicated that strains LS1R47T and LS1R49T represented two novel species within the genus Flavobacterium. Therefore, we propose two novel species, Flavobacterium frigoritolerans sp. nov. (LS1R47T=CGMCC 1.11577T=NBRC 113654T) and Flavobacterium shii sp. nov. (LS1R49T=CGMCC 1.11581T=NBRC 113652T).
Keywords: Flavobacterium; cold-adapted bacteria; glacier.