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Title: BACTERIAL CONTAMINANTS AND BIOFILM FORMATION IN FUEL ETHANOL PLANTS

Author
item Skinner, Kelly
item Leathers, Timothy

Submitted to: Regional Meeting of American Chemical Society
Publication Type: Abstract Only
Publication Acceptance Date: 10/20/2004
Publication Date: 10/20/2004
Citation: Skinner, K.A., Leathers, T.D. 2004. Bacterial contaminants and biofilm formation in fuel ethanol plants [abstract]. 36th Great Lakes Regional Meeting of American Chemical Society, October 17-20, 2004, Peoria, Illinois. p. 71.

Interpretive Summary:

Technical Abstract: Bacterial contamination is an ongoing problem for commercial fuel ethanol production facilities. Both chronic and acute infections are of concern, due to the fact that bacteria compete with the ethanol-producing yeast for sugar substrates and micronutrients. While control of the contamination is the ultimate goal, one first needs to identify and characterize contaminants. Lactic acid levels often rise during bouts of contamination, suggesting that the most common contaminants are lactic acid bacteria. However, quantitative surveys on the natural occurrence of bacteria in commercial corn-based fuel ethanol production facilities were lacking. Samples were collected from one wet mill and two dry grind fuel ethanol facilities over a nine month period at strategic time points and locations along production lines, and bacterial contaminants were isolated and identified. Lactobacillus species were indeed found to be the most abundant isolates from all three plants, averaging 51%, 38%, and 77% of total isolates from the wet mill and the first and second dry grind facilities, respectively. Antibiotic use did not seem to lower the overall amount of bacterial contamination, but may have reduced the diversity of species. In addition, individual facilities tended to exhibit characteristic bacterial profiles, suggesting the occurrence of persistent endemic infections typical of biofilms. To investigate that possibility, bacterial contaminants of commercial fuel ethanol production were found for the first time to form biofilms under laboratory conditions. Both planktonic isolates from the production facility and isolates recovered from biofilm test coupons were identified. Although lactic acid bacteria predominate in both environments, preliminary data suggest there is less diversity in biofilm populations. In addition, biofilms populations show an increase in certain Lactobacillus species, along with the appearance of new species not seen in planktonic populations.