Standard oil recovery methods typically extract only one-third of the oil originally present in a reservoir. The physical reasons for this have driven the development of many chemical processes to enhance recovery. Most of these methods rely on relatively expensive additives, making field implementation economically unattractive. Introducing microbes into the reservoir in order to produce recovery-enhancing chemicals in situ could reduce costs, but taking advantage of this potential requires great improvements over the current performance of microbial systems.