Two slime-producing bacteria capable of utilizing petroleum hydrocarbons as a sole carbon source were isolated from the drain of a crude oil storage cavity. The bacteria (designed strains SLI and SLK) were identified as Pseudomonas sp. on the basis of physiological characterization and phylogenetic analysis of the 16S rRNA sequences. They produced sugars in an inorganic medium in the presence of crude oils and alcohols. The exopolysaccharide (EPS) produced by strain SLI was purified and characterized. It consisted of one major component with a molecular weight of approximately 300 kD and was composed of glucose, galactose, mannose, ribulose, N-acetylglucosamine, xylose, and N-acetylgalactosamine in the ratios of 9.9:1:3.0:4.6:1.6:1.5:2.1. The EPS accumulated at the oil/water interface where it formed a ropy slime. It is assumed that the slime protects bacterial cells from direct exposure to toxic oil substances.