Title: Contamination issues in a continuous ethanol production corn wet milling facility Authors
|Khullar, Esha -|
|Kent, Angela -|
|Rausch, Kent -|
|Tumbleson, M -|
|Singh, Vijay -|
Submitted to: World Journal of Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 17, 2012
Publication Date: May 1, 2013
Citation: Khullar, E., Kent, A.D., Leathers, T.D., Bischoff, K.M., Rausch, K.D., Tumbleson, M.E., Singh, V. 2013. Contamination issues in a continuous ethanol production corn wet milling facility. World Journal of Microbiology and Biotechnology. 29(5):891-898. Interpretive Summary: Contamination issues can reduce the economic viability of fuel ethanol production from corn; in this research, we discovered that low ethanol yields and poor yeast viability at a continuous ethanol production corn wet milling facility were related to the presence of a contaminating microorganism. New approaches are needed to identify and control contaminants of fuel ethanol production, which reduce ethanol yields and can lead to stuck fermentations. Model fermentations and selective microbial culturing methods indicated the presence of a contaminating microorganism, which was confirmed by advanced molecular biology approaches. These results are important to researchers developing improved methods to identify and control contamination of fuel ethanol production.
Technical Abstract: Low ethanol yields and poor yeast viability were investigated at a continuous ethanol production corn wet milling facility. Using starch slurries and recycle streams from a commercial ethanol facility, laboratory hydrolysates were prepared by reproducing starch liquefaction and saccharification steps in the laboratory. Fermentations with hydrolysates prepared in the laboratory were compared with plant hydrolysates for final ethanol concentrations and total yeast counts. Fermentation controls were prepared using hydrolysates (plant and laboratory) that were not inoculated with yeast. Hydrolysates prepared in the laboratory resulted in higher final ethanol concentrations (15.8% v/v) than plant hydrolysate (13.4% v/v). Uninoculated controls resulted in ethanol production from both laboratory (12.2% v/v) and plant hydrolysates (13.7% v/v), indicating the presence of a contaminating microorganism. Yeast colony counts on cycloheximide and virginiamycin plates confirmed the presence of a contaminant. DNA sequencing and fingerprinting studies also indicated a number of dissimilar communities in samples obtained from fermentors, coolers, saccharification tanks, and thin stillage.