원문정보
초록
영어
Xylitol is a five-carbon sugar alcohol to be used as a sugar substitute because of its low caloric and anti-cariogenic properties. In this study, the effects of NAD(P)H regeneration on xylitol production were investigated by overexpression of glycolytic enzymes such as ALD6, ACS1 and GPD1 in recombinant Saccharomyces cerevisiae expressing Pichia stipitis xylose reductase (XR). The ALD6 and ACS1 genes encoding aldehyde dehydrogenase and acetyl-CoA synthetase, respectively were PCR-amplified from the genomic DNA of S. cerevisiae. The GPD1 gene coding for NADP+- dependent glyceraldehyde-3-phosphate dehydrogenase was originated from Kluyveromyces lactis. Each gene was introduced into the chromosome of S. cerevisiae BJ3505:δXR and expressed under the control of the GPD promoter. A glucose-limited fed-batch fermentation was performed in a 3.7 L-bioreactor with a complex medium containing 20 g/L glucose and 100 g/L xylose. Among three xylitol-producing systems, recombinant S. cerevisiae co-expressing XR and ACS1 produced a best xylitol concentration of 94.3 g/L at 1.62 g/L-hr its productivity, which were 1.2 and 1.3 times higher than those for the recombinant S. cerevisiae expressing XR only.