Contamination issues in a continuous ethanol production corn wet milling facility

Esha Khullar, Angela D. Kent, Timothy D. Leathers, Kenneth M. Bischoff, Kent D. Rausch, M. E. Tumbleson, Vijay Singh

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish (US)
Pages (from-to)891-898
Number of pages8
JournalWorld Journal of Microbiology and Biotechnology
Issue number5
StatePublished - 2013


  • Contamination
  • Ethanol
  • Wet milling

ASJC Scopus subject areas

  • Biotechnology
  • Physiology
  • Applied Microbiology and Biotechnology


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