21 research outputs found
A Study on Scenario Development Applied to Train Operation Methods Based on Train Accidents Analysis
์ฌ์กฐํฉ ํจ๋ชจ๋ฅผ ์ด์ฉํ ์์ผ๋ฆฌํจ ์์ฐ์์ transhydrogenase๊ฐ ๋ฏธ์น๋ ์ํฅ
Thesis (master`s)--์์ธ๋ํ๊ต ๋ํ์ :๋์๋ช
๊ณตํ๋ถ,2003.Xylitol is a five-carbon sugar alcohol which is widely present in nature.
Xylitol has been used as a sugar substitute in the food industry due to a number
of functional properties.
Xylose conversion to xylitol might be controlled by the supply of NAD(P)H in
recombinant Saccharomyces cerevisiae containing the xylose reductase gene. This
thesis is concerned with effects of simultaneous expression of Azotobactor
vinelandii soluble pyridine nucleotide transhydrogenase (STH) on xylitol
production in recombinant S. cerevisiae harboring multi copies of the Pichia
stipitis xylose reductase gene (XYL1).
The STH gene which encodes an enzyme able to transfer hydrogen ion from NADH to
NADPH in a reversible manner, was expressed in the recombinant S. cerevisiae
BJ3505:ยฅรคXR. Xylitol productivity was compared between S. cerevisiae BJ3505:ยฅรคXR
and S. cerevisiae BJ3505:ยฅรคXR/STH in batch and fed-batch fermentations. The
growth profiles and specific XR activity were not significantly different
between the two strains in batch culture. The specific STH activity of S.
cerevisiae BJ3505:ยฅรคXR/STH was 2.0 unit per mg protein.
In fed-batch fermentations, xylitol production patterns were quite different.
A final xylitol concentration for S. cerevisiae BJ3505:ยฅรคXR/STH was 59.9 g/L,
corresponding to 71% of that obtained with the S. cerevisiae BJ3505:ยฅรคXR (84.2
g/L). Xylitol productivity of S. cerevisiae BJ3505:ยฅรคXR/STH (1.4 g/L hr-1) was
only two-thirds than that of S. cerevisiae BJ3505:ยฃยฟR (2.1 g/L hr-1). S.
cerevisiae BJ3505:ยฅรคXR/STH produced more by-products than the strain without the
STH gene. 4.0 g/L acetate and 16.2 g/L ethanol were produced in the S.
cerevisiae BJ3505:ยฅรคXR/STH compared with a negligible level of acetate and 7.2
g/L ethanol for S. cerevisiae BJ3505:ยฅรคXR. The specific XR activity was almost
the same for the two strains as observed in the batch culture. The specific STH
activity was determined approximately 3.0 unit per mg cellular protein in the S.
cerevisiae BJ3505:ยฅรคXR/STH. The experimental results suggested that cytoplasmic
soluble pyridine nucleotide transhydrogenase directed the reaction toward the
formation of NADH and NADP+ from NAD+ and NADPH, which concomitantly reduced the
availability of NADPH for xylitol production in the recombinant S. cerevisiae
expressing the STH gene.Maste
The Study on the development of wave optics` simulation tool and its application to physics education
ํ์๋
ผ๋ฌธ(๋ฐ์ฌ)--์์ธ๋ํ๊ต ๋ํ์ :๊ณผํ๊ต์ก๊ณผ(๋ฌผ๋ฆฌ์ ๊ณต),1997.Docto