Affiliation:
1. Center for Process Biotechnology, BioCentrum-DTU, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
Abstract
ABSTRACT
Cofactor imbalance impedes xylose assimilation in
Saccharomyces cerevisiae
that has been metabolically engineered for xylose utilization. To improve cofactor use, we modified ammonia assimilation in recombinant
S. cerevisiae
by deleting
GDH1
, which encodes an NADPH-dependent glutamate dehydrogenase, and by overexpressing either
GDH2
, which encodes an NADH-dependent glutamate dehydrogenase, or
GLT1
and
GLN1
, which encode the GS-GOGAT complex. Overexpression of
GDH2
increased ethanol yield from 0.43 to 0.51 mol of carbon (Cmol) Cmol
−1
, mainly by reducing xylitol excretion by 44%. Overexpression of the GS-GOGAT complex did not improve conversion of xylose to ethanol during batch cultivation, but it increased ethanol yield by 16% in carbon-limited continuous cultivation at a low dilution rate.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
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