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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVING BIOCHEMICAL PROCESSES FOR THE PRODUCTION OF SUSTAINABLE FUELS AND CHEMICALS

Location: Renewable Product Technology Research Unit

Title: Application of bacteriophage endolysins to reduce Lactobacillus contamination during fuel ethanol fermentation

Authors
item Khatibi, Piyum
item Roach, Dwayne
item Donovan, David
item Hughes, Stephen
item Bischoff, Kenneth

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 20, 2014
Publication Date: N/A

Technical Abstract: Bacterial contamination is a recurring problem in the fuel ethanol industry. The offending microbes are generally species of lactic acid bacteria that drain the sugar available for conversion to ethanol and scavenge essential micronutrients required for optimal yeast growth. Antibiotics are frequently used to control bacterial contamination but extensive use of antibiotics may select for strains with decreased susceptibility to these agents. Bacteriophage endolysins are enzymes that hydrolyze the peptidoglycan of the bacterial cell wall, and can serve as an alternative to antibiotics. Genes encoding the Lactobacillus bacteriophage endolysins LysA and LysA2 were individually expressed in Saccharomyces cerevisiae on multi-copy plasmids under the control of a galactose-inducible promoter. Strains expressing either LysA or LysA2 reduced the concentration of Lactobacillus fermentum in experimentally infected fermentations using corn mash as a substrate. Lactic acid and acetic acid levels were also reduced in all experimentally infected fermentations containing transformed yeast relative to those with untransformed yeast. The reduction of bacterial load during fermentation could be enhanced by mechanical lysis of a portion of the fermentation culture, emphasizing the need to increase the effective extracellular concentration of lysin. Endolysins have application as antibacterial agents in corn-based ethanol production as well as the emerging lignocellulosic biofuel industry.

Last Modified: 9/10/2014
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