Uncoupling glucose sensing from GAL metabolism for heterologous lactose fermentation in Saccharomyces cerevisiae
Objectives Development of a system for direct lactose to ethanol fermentation provides a market for the massive amounts of underutilized whey permeate made by the dairy industry. For this system, glucose and galactose metabolism were uncoupled in Saccharomyces cerevisiae by deleting two negative reg...
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Published in | Biotechnology letters Vol. 43; no. 8; pp. 1607 - 1616 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Dordrecht
Springer Netherlands
01.08.2021
Springer Nature B.V |
Subjects | |
Online Access | Get full text |
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Summary: | Objectives
Development of a system for direct lactose to ethanol fermentation provides a market for the massive amounts of underutilized whey permeate made by the dairy industry. For this system, glucose and galactose metabolism were uncoupled in
Saccharomyces cerevisiae
by deleting two negative regulatory genes,
GAL80
and
MIG1,
and introducing the essential lactose hydrolase
LAC4
and lactose transporter
LAC12
, from the native but inefficient lactose fermenting yeast
Kluyveromyces marxianus
.
Results
Previously, integration of the
LAC4
and
LAC12
genes into the
MIG1
and
NTH1
loci was achieved to construct strain AY-51024M. Low rates of lactose conversion led us to generate the
Δmig1Δgal80
diploid mutant strain AY-GM from AY-5, which exhibited loss of diauxic growth and glucose repression, subsequently taking up galactose for consumption at a significantly higher rate and yielding higher ethanol concentrations than strain AY-51024M. Similarly, in cheese whey permeate powder solution (CWPS) during three, repeated, batch processes in a 5L bioreactor containing either 100 g/L or 150 g/L lactose, the lactose uptake and ethanol productivity rates were both significantly greater than that of AY-51024M, while the overall fermentation times were considerably lower.
Conclusions
Using the Cre-loxp system for deletion of the
MIG1
and
GAL80
genes to relieve glucose repression, and
LAC4
and
LAC12
overexpression to increase lactose uptake and conversion provides an efficient basis for yeast fermentation of whey permeate by-product into ethanol. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0141-5492 1573-6776 |
DOI: | 10.1007/s10529-021-03136-8 |