Rhodonellum psychrophilum gen. nov., sp. nov., a novel psychrophilic and alkaliphilic bacterium of the phylum Bacteroidetes isolated from Greenland.

A novel alkaliphilic and psychrophilic bacterium was isolated from the cold and alkaline ikaite tufa columns of the Ikka Fjord in south-west Greenland. According to 16S rRNA gene sequence analysis, strain GCM71(T) belonged to the family 'Flexibacteraceae' in the phylum Bacteroidetes. Strain GCM71(T), together with five related isolates from ikaite columns, formed a separate cluster with 86-93 % gene sequence similarity to their closest relative, Belliella baltica. The G+C content of the DNA from strain GCM71(T) was 43.1 mol%, whereas that of B. baltica was reported to be 35 mol%. DNA-DNA hybridization between strain GCM71(T) and B. baltica was 9.5 %. The strain was red pigmented, Gram-negative, strictly aerobic with non-motile, rod-shaped cells. The optimal growth conditions for strain GCM71(T) were pH 9.2-10.0, 5 degrees C and 0.6 % NaCl. The fatty acid profile of the novel strain was dominated by branched and unsaturated fatty acids (90-97 %), with a high abundance of iso-C(17 : 1)omega9c (17.5 %), iso-C(17 : 0) 3-OH (17.5 %) and summed feature 3, comprising iso-C(15 : 0) 2-OH and/or C(16 : 1)omega7c (12.6 %). Phylogenetic, chemotaxonomic and physiological characteristics showed that the novel strain could not be affiliated to any known genus. A new genus, Rhodonellum gen. nov., is proposed to accommodate the novel strain. Strain GCM71(T) (=DSM 17998(T)=LMG 23454(T)) is proposed as the type strain of the type species, Rhodonellum psychrophilum sp. nov.