Oil is a crucial source of energy and one of the main factors driving the world’s economy. Currently, oil production technologies recover only about 40% of the oil originally present in the reservoirs. As the price of petroleum increases and petroleum reserves shrink, exploitation of oil resources in mature reservoirs is essential for meeting future energy demands. Consequently, in the last few years more attention has been focused on enhanced oil recovery (EOR) techniques to mobilize entrapped oil from mature reservoirs. EOR generally involves the use of chemical agents that interfere with the reservoir wettability, pressure and permeability. However, these processes are expensive and often environmentally hazardous. Microbial enhanced oil recovery (MEOR) represents a cost-effective and eco-friendly alternative in which selected microbial strains are used to synthesize compounds analogous to the EOR chemicals to increase the recovery of oil from depleted and marginal reservoirs, thereby extending their life.