The　release　of　methyl　tert-butyl-ether　(MTBE)　into　the　environment　has　increased　the　worldwide　concern　about　the　pollution　of　MTBE.　In　this　paper,　a　microbial　consortium　was　isolated　from　the　soil　sample　near　an　oil　station,　which　can　degrade　MTBE　directly　with　a　low　biomass　yield　and　MTBE　degrading　efficiency.　Further　research　has　indicated　that　this　consortium　can　degrade　MTBE　efficiently　when　grown　on　n-octane　as　the　cometabolic　substrate.　The　results　of　16S　rDNA　based　on　phylogenetic　analysis　of　the　selected　operating　taxonomic　units　(OTUs)　involved　in　the　consortium　revealed　that　one　OTU　was　related　to　Pseudomonas　putida　GPo1,　which　could　cometabolically　degrade　MTBE　on　the　growth　of　n-octane.　This　may　help　explain　why　n-octane　could　be　the　optimal　cometabolic　substrate　of　the　consortium　for　MTBE　degradation.　Furthermore,　the　degradation　of　MTBE　was　observed　along　with　the　consumption　of　n-octane.　Different　Ks　values　for　MTBE　were　observed　for　cells　grown　with　or　without　n-octane,　suggesting　that　different　enzymes　are　responsible　for　the　oxidation　of　MTBE　in　cells　grown　on　n-octane　or　MTBE.　The　results　are　discussed　in　terms　of　their　impacts　on　our　understanding　of　MTBE　biodegradation　and　cometabolism.