A psychrotolerant, obligately alkaliphilic, collagenolytic enzyme-producing bacterium, strain AC40(T), was isolated from a deep-sea sediment off Torishima Island, Japan, at a depth of 4026 m. Phylogenetic analysis of 16S rRNA gene sequences indicated that this bacterium was closely related to members of the genus Alkalimonas, with highest sequence similarity (97.9 %) to Alkalimonas delamerensis 1E1(T). DNA-DNA hybridization experiments of strain AC40(T) with A. delamerensis 1E1(T) revealed a level of relatedness of less than 30 %. Cells of strain AC40(T) were strictly aerobic, rod-shaped, Gram-negative and motile by means of a single polar flagellum. The organism grew over a range of temperatures from 5 to 37 degrees C and at initial pH values between 7.0 and 10.5. Optimal growth was observed at 33 degrees C and at pH 8.5-10.0. Cellular fatty acids of strain AC40(T) were predominantly saturated and mono-unsaturated straight-chain components (C(16 : 0) and C(18 : 1)). The major isoprenoid quinone was Q-8. The G+C content of the DNA was 49.3 mol%. Phylogenetic characteristics, physiological properties and DNA-DNA hybridization data indicate that strain AC40(T) represents a novel species of the genus Alkalimonas, for which the name Alkalimonas collagenimarina sp. nov. is proposed. The type strain is AC40(T) (=JCM 14267(T)=NCIMB 14266(T)).