A facultatively psychrophilic bacterium, strain MD17(T), which hydrolyses lipids at 5 degrees C, was isolated from the Monbetsu coast of the Okhotsk Sea in Hokkaido, Japan, when ice carried by the cold current came to the area. The isolate is an aerobic, non-motile coccobacillus that reduces nitrate to nitrite and hydrolyses Tweens 20, 40, 60 and 80, but not gelatin, DNA or alginic acid. The isolate grows at 0 degrees C, but not at temperatures higher than 36 degrees C; its optimum growth temperature is 25 degrees C. It grows in the presence of 0-10 % NaCl. Its major isoprenoid quinone is ubiquinone-8 (Q-8) and its DNA G+C content is 46.7 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain MD17(T) is closely related to Psychrobacter glacincola DSM 12194(T) (99.0 % similarity) and Psychrobacter immobilis DSM 7229(T) (98.7 % similarity). DNA-DNA hybridization revealed 45.9 % relatedness between strain MD17(T) and P. immobilis ATCC 43116(T) and 33.4 % between strain MD17(T) and P. glacincola ATCC 700754(T). Based on physiological and biochemical characteristics, phylogenetic position (as determined by 16S rRNA gene sequence analysis) and DNA-DNA relatedness, it is concluded that the isolate should be designated as a novel species, for which the name Psychrobacter okhotskensis sp. nov. is proposed. The type strain is MD17(T) (=NCIMB 13931(T)=JCM 11840(T)).