Characterization of several Psychrobacter strains isolated from Antarctic environments and description of Psychrobacter luti sp nov and Psychrobacter fozii sp nov.

Eleven psychrophilic bacteria isolated from Antarctic coastal marine environments were subjected to a polyphasic taxonomic study. The isolates were oxidase-positive, halotolerant, Gram-negative, non-motile coccobacilli with a strictly oxidative metabolism. The DNA G+C content ranged from 44 to 47 mol%. DNA-DNA hybridization experiments showed six homology groups, two of them related at the species level to the type strain of Psychrobacter immobilis, LMG 7203(T) (70-83 %). The highest DNA relatedness of two other groups to known Psychrobacter species was found to the type strain of Psychrobacter glacincola, LMG 21282(T) (51-57%), and no significant similarity was found between Psychrobacter type strains and the last two groups. The predominant cellular fatty acids detected were typical of the genus Psychrobacter and included 18:1omega9c, 16:1omega7c and 17:1omega8c. 16S rRNA gene sequence analysis confirmed that the strains isolated belonged to the genus Psychrobacter. The results of the study assigned five isolates to P. immobilis, three isolates to P. glacincola and three isolates to novel Psychrobacter species. The names Psychrobacter luti sp. nov. (type strain NF11(T)=LMG 21276(T)=CECT 5885(T)) and Psychrobacter fozii sp. nov. (type strain NF23(T)=LMG 21280(T)=CECT 5889(T)) are proposed for these organisms.