Four psychrotrophic strains, which grew at 4 degreesC but not at 37 degreesC, were isolated from Japanese oil-reservoir water (strains SIB1, SIC1, SIS1) and Canadian oil sands (strain CAB1). Strains SIB1, SIS1, and CAB1 had a maximum growth rate at 20 degreesC and grew to the highest cell densities at the cultivation temperature of 0-4 degreesC. Strain SIS1 was capable of growing even at -5 degreesC. The growth profile of strain SIC I was rather similar to that of a mesophilic bacterium. Strains SIB1, SIC1, and SIS1 were identified as members of the genus Shewanella, and strain CAB1 was a member of the genus Arthrobacter. All these strains exhibited weak degradation ability against catechol, a hydroxylated aromatic hydrocarbon, and tributyrin. These strains are expected to be of potential use in the in situ bioremediation technology of hazardous hydrocarbons and esters under low-temperature conditions.