A Gram-negative, motile, rod-shaped, psychrophilic and weakly halophilic bacterial strain, SL13(T), was isolated from deep-sea sediments (1450 m depth) of Edison Seamount in the western Pacific Ocean. Optimal growth of SL13(T) requires the presence of 1.5% (w/v) NaCl, a pH of 6.0 and a temperature of 14 degrees C. The whole-cell fatty acid profile of the isolate includes C16:1 and C16:0 as major fatty acids and contains C20:5omega3. This is consistent with corresponding data for Photobacterium profundum. The DNA G+C content of strain SL13(T) is 43.8 mol%. Phylogenetic analyses of 16S rRNA gene sequences place this bacterium in the 'Gammaproteobacteria', within the genus Photobacterium. Sequence similarity analysis indicates that the closest relatives of strain SL13(T) are Photobacterium indicum (99.3%), P. profundum (98.5%) and Photobacterium lipolyticum (98.2%). The DNA-DNA hybridization levels between the isolate and its closest known phylogenetic relatives, P. indicum, P. profundum and P. lipolyticum, are 27.1, 52.4 and 20.2%, respectively. Thus strain SL13(T) represents a novel species of the genus Photobacterium, for which the name Photobacterium frigidiphilum sp. nov. is proposed. The type strain is SL13(T) (=KCTC 12384(T)=JCM 12947(T)).