MTBE is used as a fuel additive in gasoline for promoting com- bustion. Despite the improved quality of the air sine MTBE is being used in 1970, his properties are the cause that current existing physicochemical techniques are not capable of efficient remediation of MTBE contaminated soil and groundwater. This project aims to obtain knowledge on the microbial communities, degradation processes and process parameters that play a role in the aerobic biodegradation of MTBE under in situ bioremediation conditions. Special attention will be payed to the use of ORC. We aim the isolation and characterisation of bacterial cultures for in situ bioaugmentation purposes of MTBE contaminated aquifers. The influence of other gasoline components on the degradation of MTBE and vice versa will be studied.