Glaciibacter superstes gen. nov., sp. nov., a novel member of the family Microbacteriaceae isolated from a permafrost ice wedge.

Gram-positive, aerobic, non-spore-forming, irregular rod-shaped bacteria, designated strains AHU1791(T) and AHU1810, were isolated from a permafrost ice wedge in Alaska. Cells were motile by means of a polar flagellum. The strains were psychrophilic, growing at -5 to 25 degrees C. Phylogenetic analysis of 16S rRNA gene sequences indicated that the ice-wedge isolates formed a clade distinct from other genera affiliated with the family Microbacteriaceae. The novel strains showed highest levels of 16S rRNA gene sequence similarity with members of the genera Agreia and Subtercola (95.6-95.9 %). The level of 16S rRNA gene sequence similarity between strains AHU1791(T) and AHU1810 was 99.8 %. The cell-wall peptidoglycan type of the two strains was B2gamma, containing 2,4-diaminobutyric acid as the diagnostic amino acid. The predominant menaquinones were MK-12 and MK-13 (strain AHU1791(T)) and MK-11 and MK-12 (strain AHU1810). The major fatty acids of the two strains were 12-methyl tetradecanoic acid (anteiso-C(15 : 0)), 14-methyl hexadecanoic acid (anteiso-C(17 : 0)), 14-methyl pentadecanoic acid (iso-C(16 : 0)) and 13-methyl tetradecanoic acid (iso-C(15 : 0)). The DNA G+C contents of strains AHU1791(T) and AHU1810 were approximately 65 mol%. These phenotypic characteristics differentiated the ice-wedge strains from their closest phylogenetic neighbours, namely Subtercola boreus and the two recognized species of the genus Agreia. The sequences of the housekeeping genes coding for DNA gyrase subunit B (gyrB), RNA polymerase subunit B (rpoB) and recombinase A (recA) were almost identical between strains AHU1791(T) and AHU1810. Although the predominant menaquinones found in strains AHU1791(T) and AHU1810 were different, no other distinct differences were found with regard to other phenotypic and genotypic characteristics, indicating that the two strains were members of the same species. Accordingly, strains AHU1791(T) and AHU1810 are considered to represent a single novel species of a new genus, for which the name Glaciibacter superstes gen. nov., sp. nov. is proposed. The type strain of Glaciibacter superstes is AHU1791(T) (=DSM 21135(T) =NBRC 104264(T)).