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Published on: April 22, 2016
Xylitol production by recombinant Corynebacterium glutamicum under oxygen deprivation
Miho Sasaki1, Toru Jojima, Masayuki Inui
1Research Institute of Innovative Technology for the Earth, 9-2 Kizugawadai, Kizugawa, Kyoto, Japan.
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.
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