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Viruses 2018, 10(6), 281;

Yeast Derived LysA2 Can Control Bacterial Contamination in Ethanol Fermentation

Department of Food Science and Human Nutrition, University of Illinois, 905 S. Goodwin Ave., Urbana, IL 61801, USA
Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 W. Gregory Dr., Urbana, IL 61801, USA
Author to whom correspondence should be addressed.
Received: 19 February 2018 / Revised: 2 May 2018 / Accepted: 17 May 2018 / Published: 24 May 2018
(This article belongs to the Special Issue Phage Lytic Enzymes and Their Applications)
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Contamination of fuel-ethanol fermentations continues to be a significant problem for the corn and sugarcane-based ethanol industries. In particular, members of the Lactobacillaceae family are the primary bacteria of concern. Currently, antibiotics and acid washing are two major means of controlling contaminants. However, antibiotic use could lead to increased antibiotic resistance, and the acid wash step stresses the fermenting yeast and has limited effectiveness. Bacteriophage endolysins such as LysA2 are lytic enzymes with the potential to contribute as antimicrobials to the fuel ethanol industries. Our goal was to evaluate the potential of yeast-derived LysA2 as a means of controlling Lactobacillaceae contamination. LysA2 intracellularly produced by Pichia pastoris showed activity comparable to Escherichia coli produced LysA2. Lactic Acid Bacteria (LAB) with the A4α peptidoglycan chemotype (L-Lys-D-Asp crosslinkage) were the most sensitive to LysA2, though a few from that chemotype were insensitive. Pichia-expressed LysA2, both secreted and intracellularly produced, successfully improved ethanol productivity and yields in glucose (YPD60) and sucrose-based (sugarcane juice) ethanol fermentations in the presence of a LysA2 susceptible LAB contaminant. LysA2 secreting Sacharomyces cerevisiae did not notably improve production in sugarcane juice, but it did control bacterial contamination during fermentation in YPD60. Secretion of LysA2 by the fermenting yeast, or adding it in purified form, are promising alternative tools to control LAB contamination during ethanol fermentation. Endolysins with much broader lytic spectrums than LysA2 could supplement or replace the currently used antibiotics or the acidic wash. View Full-Text
Keywords: endolysin; Saccharomyces cerevisiae; biofuel; Lactobacillus fermentum; fermentation; Pichia pastoris; secretion; endopeptidase; sugarcane endolysin; Saccharomyces cerevisiae; biofuel; Lactobacillus fermentum; fermentation; Pichia pastoris; secretion; endopeptidase; sugarcane

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Kim, J.-S.; Daum, M.A.; Jin, Y.-S.; Miller, M.J. Yeast Derived LysA2 Can Control Bacterial Contamination in Ethanol Fermentation. Viruses 2018, 10, 281.

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