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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Renewable Product Technology Research » Research » Publications at this Location » Publication #317981
Title: Biofilm formation and ethanol inhibition by bacterial contaminants of biofuel fermentation

Author
item Rich, Joseph
item Leathers, Timothy
item Bischoff, Kenneth
item Anderson, Amber
item Nunnally, Melinda

Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2015
Publication Date: 11/1/2015
Publication URL: http://handle.nal.usda.gov/10113/5695392
Citation: Rich, J.O., Leathers, T.D., Bischoff, K.M., Anderson, A.M., Nunnally, M.S. 2015. Biofilm formation and ethanol inhibition by bacterial contaminants of biofuel fermentation. Bioresource Technology. 196:347-354.

Interpretive Summary: A two-year study was conducted of bacterial contaminants from a Midwestern dry grind corn fuel ethanol facility. New methods are needed to control contaminants of fuel ethanol production, which reduce ethanol yields and can lead to stuck fermentations. Results showed that ethanol inhibition appeared to be related to acetic acid production by certain species of lactic acid bacteria. These results are important to researchers developing improved methods to control contamination of fuel ethanol production.

Technical Abstract: Bacterial contaminants can inhibit ethanol production in biofuel fermentations, and even result in stuck fermentations. Contaminants may persist in production facilities by forming recalcitrant biofilms. A two-year longitudinal study was conducted of bacterial contaminants from a Midwestern dry grind corn fuel ethanol facility. Among eight sites sampled in the facility, the combined liquefaction stream and yeast propagation tank were consistently contaminated, leading to contamination of early fermentation tanks. Seven hundred and sixty-eight contaminants were isolated, identified to the species level, and individually characterized for their capacity to form biofilms and inhibit ethanol production. Ninety-two percent of total isolates were identified as Lactobacillus sp., with the most abundant species being L. plantarum, L. casei, L. mucosae, and L. fermentum. Seven percent of total isolates showed the ability to form biofilms in pure cultures, and 22% showed the capacity to significantly inhibit ethanol production. However, these traits were not correlated. Ethanol inhibition appeared to be related to acetic acid production by contaminants, particularly by obligately heterofermentative species such as L. fermentum and L. mucosae.