Bacterial appetites for chemical pollutants have inspired advocates of bioremediation to include "biofilters" in their recipe books for economical environmental clean-up. In a biofilter, natural oxygen-loving bacteria will digest toxins like ethanol, gasoline, phenol, dichloromethane, toluene, xylene and other airborne pollutants and burp out less toxic substances. Researching the spectrum of toxins that can be digested is the focus of a collaboration among several scientists at UC Davis. The researchers are cooking up combinations of nutrients and chemicals that, when added with water, can expand the usefulness of biofilters. For example trichloroethylene will go down without complaint only if seasoned with toluene. The biofilter approach avoids or, in some cases, reduces the need for a standard cleanup operation. Environmental engineering professors Dan Chang and Ed Schroeder; land air and water resources associate professor Kate Scow, a soil microbiologist and ecologist; and graduate student Kerry Kinney are working to expand the bacterial menu. The research is funded by California Air Resources Board, Exxon Corp. and the National Institute of Environmental Health Sciences.