Abstract
Wild-type Corynebacterium glutamicum produced 0.6 g l(-1) xylitol from xylose at a productivity of 0.01 g l(-1) h(-1) under oxygen deprivation. To increase this productivity, the pentose transporter gene (araE) from C. glutamicum ATCC31831 was integrated into the C. glutamicum R chromosome. Consequent disruption of its lactate dehydrogenase gene (ldhA), and expression of single-site mutant xylose reductase from Candida tenuis (CtXR (K274R)) resulted in recombinant C. glutamicum strain CtXR4 that produced 26.5 g l(-1) xylitol at 3.1 g l(-1) h(-1). To eliminate possible formation of toxic intracellular xylitol phosphate, genes encoding xylulokinase (XylB) and phosphoenolpyruvate-dependent fructose phosphotransferase (PTS(fru)) were disrupted to yield strain CtXR7. The productivity of strain CtXR7 increased 1.6-fold over that of strain CtXR4. A fed-batch 21-h CtXR7 culture in mineral salts medium under oxygen deprivation yielded 166 g l(-1) xylitol at 7.9 g l(-1) h(-1), representing the highest bacterial xylitol productivity reported to date.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Aldehyde Reductase / genetics
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Anaerobiosis
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Bacterial Proteins / genetics*
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Bacterial Proteins / metabolism*
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Biosynthetic Pathways / genetics*
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Candida / enzymology
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Corynebacterium glutamicum / genetics*
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Corynebacterium glutamicum / metabolism*
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Fermentation
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Fungal Proteins / genetics
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Fungal Proteins / metabolism
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Gene Knockout Techniques
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Genetic Engineering
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Hydro-Lyases / genetics
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Monosaccharide Transport Proteins / genetics
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Monosaccharide Transport Proteins / metabolism
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Oxygen / metabolism
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Phosphotransferases (Alcohol Group Acceptor) / genetics
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Phosphotransferases / genetics
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Recombination, Genetic
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Xylitol / biosynthesis*
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Xylose / metabolism
Substances
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AraE protein, bacteria
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Bacterial Proteins
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Fungal Proteins
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Monosaccharide Transport Proteins
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Recombinant Proteins
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Xylose
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Aldehyde Reductase
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Phosphotransferases
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Phosphotransferases (Alcohol Group Acceptor)
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xylulokinase
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Hydro-Lyases
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lactate dehydratase
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Oxygen
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Xylitol