Adapted bacterial consortia from activated sludge mineralized 2.8 mg ethyl tert-butyl ether (ETBE).l(-1).h whereas methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME) were not attacked. From these consortia, two bacterial strains, identified as Gordona terrae and Rhodococcus equi, were isolated. Both strains used ETBE, but not MTBE or TAME, as sole carbon and energy source. Gordona terrae and Rhodococcus equi completely converted ETBE into tertbutanol (TBA) with degradation rates up to 380 mg ETBE.g(-1) protein. h(-1). TBA was mineralized by the ETBE-adapted consortia.