This invention utilizes the filamentous fungus Graphium sp., which is one of the few organisms known to grow on gaseous n-alkanes including; ethane, propane and n-butane. The fungus, while growing on n-alkanes, can cometabolically oxidize and degrade the gasoline oxygenate, methyl tert-butyl ether (MTBE). Methods for bioremediation of MTBE-contaminated media and bioremediation systems which incorporate these organisms are included.
Background of Invention
MTBE is used as a gasoline oxygenate to reduce emissions of carbon monoxide from automobile exhaust. Current consumption of this compound in the US is approximately 25 billion pounds per year. MTBE is more water soluble than most gasoline components and has been detected in numerous groundwater supplies, presumably as the result of leaking gasoline storage tanks and accidental spills. Due to its ether bond, MTBE is very poorly biodegradable in the environment under a variety of conditions and, to date, no microorganism has been shown to degrade MTBE in pure culture. The US Environmental Protection Agency classifies MTBE as a possible human carcinogen and atmospheric releases of this compound are controlled under the Clean Air Act. The EPA has issued a health advisory for lifetime exposure to MTBE in drinking water; it now falls within 20 to 200 micrograms per liter. During a 16 state survey for 60 volatile organic compounds in groundwater, chloroform and MTBE were the two most frequently detected organics in eight urban areas sampled.