In 2001, this article was written re: the use of mushrooms to break down oil and gasoline spills. The process is called mycoremediation and was tested with the Washington State Department of Transportation in a 1998 field experiment. The results were promising.
Paul Stamets is the mycologist from Olympia, Washington who has conducted the research. With the passage of ten years and the BP Gulf oil spill in 2010, there was a great deal of additional press regarding the possible use of mycoremediation to clean up the massive oil spill. Although the process has not been tested on a large scale basis, you can read more about what we know and don’t know at http://www.fungi.com/mycotech/petroleum_problem.html .
Leslie Guttman is a staff writer for the San Francisco Chronicle. I found this article to be an easy to read overview of the process designed for the general public. The Stamets’ website is more technical in nature for those who want to understand more on the topic.