Flavobacterium weaverense sp. nov. and Flavobacterium segetis sp. nov., novel psychrophiles isolated from the Antarctic.

Two psychrophilic flavobacteria, designated AT1042(T) and AT1048(T), were isolated from terrestrial samples from the Antarctic. Results of 16S rRNA gene sequence analyses indicated a close relationship of these isolates to Flavobacterium flevense (96.9 % similarity for strain AT1042(T)) and Flavobacterium psychrolimnae (97.0 % for strain AT1048(T)). Cells were non-motile and non-gliding. Flexirubin-type pigments were absent. Both isolates were psychrophilic, with an optimum and maximum growth temperature of about 15 and 20 degrees C, respectively. The major isoprenoid quinone, predominant cellular fatty acids and DNA G+C contents (35-37 mol%) were consistent with the placement of the Antarctic isolates in the genus Flavobacterium. Phylogeny based on 16S rRNA gene sequences and several phenotypic characteristics could be used to differentiate these isolates from recognized Flavobacterium species. Despite high 16S rRNA gene sequence similarity (98.9 %) between strains AT1042(T) and AT1048(T), they represented two distinct species as demonstrated by low genomic relatedness (34 %) and a number of differential phenotypic characters. The polyphasic data presented in this study indicated that the new isolates should be classified within two novel species in the genus Flavobacterium. The names Flavobacterium weaverense sp. nov. (type strain AT1042(T) = IMSNU 14048(T) = KCTC 12223(T) = JCM 12384(T)) and Flavobacterium segetis sp. nov. (type strain AT1048(T) = IMSNU 14050(T) = KCTC 12224(T) = JCM 12385(T)) are proposed for these Antarctic isolates.