Degradation of ethanol plant by-products by Exophiala lecanii-corni and Saccharomyces cerevisiae in batch studies.

By-product emissions from ethanol production facilities have become a public health concern. Many of these by-products are classified as hazardous air pollutants by the USEPA and current treatment methods, mainly thermal-oxidation, for these compounds are costly, energy intensive, and may produce other undesirable by-products. Degradation of these by-products by the fungi Exophiala lecanii-corni and Saccharomyces cerevisiae was explored. Ethanol plant by-products, focused on in this study, included formaldehyde, acetaldehyde, ethanol, methanol, glycerol, acetic acid, and lactic acid. Initial batch studies were conducted to determine degradation rates and whether the contaminants would be toxic to the fungi. These batch studies demonstrated that E. lecanii-corni and S. cerevisiae are able to utilize all but methanol and formaldehyde as sole carbon and energy sources for growth; however, both contaminants were utilized as secondary metabolites by cultures initially fed either ethanol or acetic acid. Growth studies also were conducted using two contaminants simultaneously to determine if the presence of one contaminant inhibited the degradation of another. Growth and contaminant utilization was observed in cultures fed two contaminants simultaneously.