Flavobacterium psychraerolatum sp. nov., Flavobacterium aeripolare sp. nov. and Flavobacterium gelidicaeli sp. nov. isolated from Antarctic air

Four aerobic, Gram-stain-negative, non-motile, rod-shaped, psychrophilic and yellow to light orange-pigmented bacterial strains, designated 7Aᵀ, 14Aᵀ, 28Aᵀ and 7E, were isolated from air samples collected at Fildes Peninsula, King George Island, Antarctica. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the novel strains were related to members of the genus Flavobacterium , and revealed that strain 7A ^T shared 98.40% similarity to F. faecale WV33 ^T , while strains 14A ^T , 28A ^T and 7E showed 98.88%, 98.74% and 98.61% similarity, respectively, to F. frigidarium A2i ^T . The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between these novel isolates and their closest relatives were below the cut-off values used for species delineation of 95-96% and 70%, respectively. Moreover, the ANI and dDDH values between strains 28A ^T and 7E were 97.62 and 78.30%, respectively, indicating that these strains represented the same species. All four strains contained menaquinone-6 as the sole respiratory quinone. The DNA G+C content of all strains ranged from 32.8 to 34.5 mol%. Based on phylogenetic, genomic and phenotypic data, we propose that strains 7Aᵀ, 14Aᵀ and 28Aᵀ represent three novel species of the genus Flavobacterium , for which the names Flavobacterium psychraerolatum (7A ^T =CCM 8976 ^T =DSM 111734 ^T ), Flavobacterium aeripolare (14A ^T =CCM 8972 ^T =CGMCC 1.18502 ^T ) and Flavobacterium gelidicaeli (28A ^T =CCM 8973 ^T =CGMCC 1.18503 ^T ) are proposed.