Rhodoglobus vestalii gen. nov., sp nov., a novel psychrophilic organism isolated from an Antarctic Dry Valley lake

A novel, psychrophilic, Gram-positive bacterium (designated strain LV3(T)) from a lake near the McMurdo Ice Shelf, Antarctica, has been isolated and characterized. This organism formed red-pigmented colonies, had an optimal growth temperature of 18 degreesC and grew on a variety of media between -2 and 21 degreesC. Scanning electron micrographs of strain LV3(T) that showed small rods with unusual bulbous protuberances during all phases of growth were of particular interest. The G+C content of the genomic DNA was approximately 62 mol%. The cell walls contained ornithine as the diamino acid. The major fatty acids were anteiso-C-15:0, iso-C-16:0 and anteiso-C-17:0. Cells grown at -2 degreesC contained significant amounts of anteiso-C-15:1. The major menaquinones found in strain LV3(T) were MK-11 and MK-12. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain LV3(T) was a member of the family Microbacteriaceae and related to, but distinct from, organisms belonging to the genera Agreia, Leifsonia and Subtercola. In addition, alignments of 16S rRNA sequences showed that the sequence of strain LV3(T) contained a 13 by insertion that was found in only a few related sequences. Based on the low growth temperature, unusual cell shape, distinct 16S rRNA gene sequence and structure and cell-wall amino acid and menaquinone compositions, Rhodoglobus vestalii gen. nov., sp. nov. is proposed, with the type strain LV3(T) (= ATCC BAA-534(T) = CIP 107482(T)).