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United States Department of Agriculture

Agricultural Research Service

Research Project: MANAGEMENT AND GENETIC CHARACTERIZATION OF AGRICULTURAL AND BIOTECHNOLOGICAL MICROBIAL RESOURCES

Location: Bacterial Foodborne Pathogens & Mycology Research Unit

Title: Screening Saccharomyces cerevisiae Distillery Strains in Industrial Media

Authors
item Abbas, Charles -
item Sparks, Martin -
item Smith, Kathy -
item Kurtzman, Cletus

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 30, 2012
Publication Date: August 30, 2012
Citation: Abbas, C.A., Sparks, M.L., Smith, K.J., Kurtzman, C.P. 2012. Screening Saccharomyces cerevisiae Distillery Strains in Industrial Media. Meeting Abstract.

Technical Abstract: Twenty-four distillery yeast strains were obtained from the ARS Culture Collection (NRRL) in Peoria, IL, and screened for ethanol production at 30 and 35°C using industrial media. The medium used in the tests consisted of corn mash prepared by combining coarse ground corn, water, and stillage from an ethanol producing facility. The pH of the stillage was adjusted to 6.0 using a 50% solution of sodium hydroxide before cooking the medium. After cooking and cooling of the preparation, the pH was adjusted to 4.5 using 4M sulfuric acid and sterilized at 121°C for 60 minutes. One hundred ml of the sterilized medium was dispensed into 250 ml non-baffled sterile flasks. Duplicate flasks were inoculated with different strains of yeasts (1×108 cells/ml). Prior to inoculation, 50 µl aliquots of glucoamylase were added to each flask. The yeast inoculum was standardized by measuring viability and cell counts were determined in a methylene blue solution. The shake flasks were incubated at 30 or 35°C with agitation set at 250 rpm. The flasks were sampled at 24, 48, and 72 hours. A peak ethanol concentration for both temperatures was observed at 48 hours with the majority of glucose being utilized by then. The top three strains of Saccharomyces cerevisiae produced ethanol in the range of 14.4-14.9% v/v at 30°C. By comparison, the top three strains produced ethanol in the range of 14.1-14.2% v/v at 35°C. At both temperatures, the highest glycerol concentration ranged from 10.3-11.2 g/l with total organic acids (acetic, lactic) in the range of 0.8-1.2 g/l. The total residual sugars remaining at 30°C were 4.7-5.6 g/l and at 35°C were 5.2-6.2 g/l. Further testing of the best selected strains is planned to establish robustness under industrial conditions in laboratory scale fermentors in batch and in continuous mode.

Last Modified: 4/19/2014
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