Affiliation:
1. Research Institute of Innovative Technology for the Earth, 9-2 Kizugawadai, Kizu-cho, Soraku-gun, Kyoto 619-0292, Japan
Abstract
ABSTRACT
The aerobic microorganism
Corynebacterium glutamicum
was metabolically engineered to broaden its substrate utilization range to include the pentose sugar xylose, which is commonly found in agricultural residues and other lignocellulosic biomass. We demonstrated the functionality of the corynebacterial
xylB
gene encoding xylulokinase and constructed two recombinant
C. glutamicum
strains capable of utilizing xylose by cloning the
Escherichia coli
gene
xylA
encoding xylose isomerase, either alone (strain CRX1) or in combination with the
E. coli
gene
xylB
(strain CRX2). These genes were provided on a high-copy-number plasmid and were under the control of the constitutive promoter
trc
derived from plasmid pTrc99A. Both recombinant strains were able to grow in mineral medium containing xylose as the sole carbon source, but strain CRX2 grew faster on xylose than strain CRX1. We previously reported the use of oxygen deprivation conditions to arrest cell replication in
C. glutamicum
and divert carbon source utilization towards product production rather than towards vegetative functions (M. Inui, S. Murakami, S. Okino, H. Kawaguchi, A. A. Vertès, and H. Yukawa, J. Mol. Microbiol. Biotechnol.
7
:182-196, 2004). Under these conditions, strain CRX2 efficiently consumed xylose and produced predominantly lactic and succinic acids without growth. Moreover, in mineral medium containing a sugar mixture of 5% glucose and 2.5% xylose, oxygen-deprived strain CRX2 cells simultaneously consumed both sugars, demonstrating the absence of diauxic phenomena relative to the new
xylA-xylB
construct, albeit glucose-mediated regulation still exerted a measurable influence on xylose consumption kinetics.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
200 articles.
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