Ethanol-induced yeast flocculation directed by the promoter of TPS1 encoding trehalose-6-phosphate synthase 1 for efficient ethanol production
Yeast flocculation is an important trait in the brewing industry as well as in ethanol production, through which biomass can be recovered by cost-effective sedimentation. However, mass transfer limitation may affect yeast growth and ethanol fermentation if the flocculation occurs earlier before ferm...
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Published in: | Metabolic engineering 2012, Vol.14 (1), p.1-8 |
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Main Authors: | , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Yeast flocculation is an important trait in the brewing industry as well as in ethanol production, through which biomass can be recovered by cost-effective sedimentation. However, mass transfer limitation may affect yeast growth and ethanol fermentation if the flocculation occurs earlier before fermentation is completed. In this article, a novel type of cell-cell flocculation induced by trehalose-6-phosphate synthase 1 (
TPS1) promoter was presented. The linear cassette
HO–
P
TPS1–
FLO1
SPSC01–
KanMX4–
HO was constructed to transform the non-flocculating industrial yeast
S. cerevisiae 4126 by chromosome integration to obtain a new flocculating yeast strain, ZLH01, whose flocculation was induced by ethanol produced during fermentation. The experimental results illustrated that flocculation of ZLH01 was triggered by 3% (v/v) ethanol and enhanced as ethanol concentration increased till complete flocculation was achieved at ethanol concentration of 8% (v/v). Real time PCR analysis confirmed that the expression of
FLO1
SPSC01 was dependent on ethanol concentration. The growth and ethanol fermentation of ZLH01 were improved significantly, compared with the constitutive flocculating yeast BHL01 engineered with the same
FLO gene but directed by the constitutive 3-phosphoglycerate kinase promoter
PGK1, particularly under high temperature conditions. These characteristics make the engineered yeast more suitable for ethanol production from industrial substrates under high gravity and temperature conditions. In addition, this strategy offers advantage in inducing differential expression of other genes for metabolic engineering applications of
S. cerevisiae.
► The promoter of
TPS1 encoding trehalose-6-phosphate synthase 1 responses to ethanol. ► The flocculation of yeast induced by ethanol exhibits good fermentation performance. ►
TPS1-directed differential gene expression is a useful strategy. |
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ISSN: | 1096-7176 1096-7184 |
DOI: | 10.1016/j.ymben.2011.12.003 |