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 7AT shared 98.40% similarity to Flavobacterium faecale WV33T, while strains 14AT, 28AT and 7E showed 98.88%, 98.74% and 98.61% similarity, respectively, to Flavobacterium frigidarium A2iT. 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 28AT 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 (7AT=CCM 8976T=DSM 111734T), Flavobacterium aeripolare (14AT=CCM 8972T=CGMCC 1.18502T) and Flavobacterium gelidicaeli (28AT=CCM 8973T=CGMCC 1.18503T) are proposed.