Abstract
We successfully demonstrated batch ethanol fermentation repeated ten times from raw starch with high ethanol productivity. We constructed a yeast diploid strain coexpressing the maltose transporter AGT1, alpha-amylase, and glucoamylase. The introduction of AGT1 allows maltose and maltotriose fermentation as well as the improvement of amylase activities. We also found that alpha-amylase activity during fermentation was retained by the addition of 10 mM calcium ion and that the highest alpha-amylase activity was 9.26 U/ml during repeated fermentation. The highest ethanol productivity was 2.22 g/l/h at the fourth batch, and after ten cycles, ethanol productivity of more than 1.43 g/l/h was retained, as was alpha-amylase activity at 6.43 U/ml.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amylases / genetics
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Amylases / metabolism*
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Biomass
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Bioreactors / microbiology*
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Diploidy
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Ethanol
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Fermentation*
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Gene Expression*
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Glucan 1,4-alpha-Glucosidase / genetics
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Glucan 1,4-alpha-Glucosidase / metabolism
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Maltose / metabolism
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Monosaccharide Transport Proteins / genetics
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Monosaccharide Transport Proteins / metabolism*
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Saccharomyces cerevisiae / enzymology
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Saccharomyces cerevisiae / genetics*
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
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Starch / metabolism*
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Symporters / genetics
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Symporters / metabolism*
Substances
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Monosaccharide Transport Proteins
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Saccharomyces cerevisiae Proteins
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Symporters
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maltose transport system, S cerevisiae
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Ethanol
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Maltose
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Starch
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Amylases
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Glucan 1,4-alpha-Glucosidase