Desulfococcus oleovorans Strain Hxd3 was isolated from the saline water phase of an oil-water separator from a northern German oil field. Hxd3 is a delta-proteobacterium capable of utilizing C12-C20 alkanes as growth substrates. Hxd3 activates alkanes via carboxylation at C3, with subsequent elimination of the terminal and subterminal carbons, yielding a fatty acid that is one carbon shorter than the parent alkane. Hxd3 is the only pure culture that is known to carboxylate aliphatic hydrocarbons.