Yazhen Zhang

Publications (2)2.5 Total impact

• Source

  Available from: life.cnu.edu.cn

  Article: Co-expression of xylose reductase gene from Candida shehatae and endogenous xylitol dehydrogenase gene in Saccharomyces cerevisiae and the effect of metabolizing xylose to ethanol

  Jinxin Zhang, Min Yang, Shen Tian, Yazhen Zhang, Xiushan Yang
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  ABSTRACT: The inability oft Saccharomyces cerevisiae to utilize xylose is attributed to its inability to convert xylose to xylulose. Low xylose reductase (XR) and xylitol dehydrogenase (XDH) activities in S. cerevisiae are regarded as the reason of blocking the pathway from xylose to xylulose. We had found that Candida shehatae could also be another source for XR gene except Pichia stipitis in the previous study. In this study, we tried to investigate if the expressed XR from C. shehatae could work with the over-expressed endogenous XDH together to achieve the same goal of converting xylose to ethanol in S. cerevisiae. The XR gene (XYL1) from C. shehatae and endogenous XDH gene (XYL2) were both cloned and over-expressed in host S. cerevisiae cell. The specific enzyme activities of XR and XDH were measured and the result of fermentation revealed that the new combination of two enzymes from different sources other than P. stipitis could also coordinate and work with each other and confer xylose utilization ability to S. cerevisiae.
  Applied Biochemistry and Microbiology 04/2012; 46(4):415-420. · 0.56 Impact Factor
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  Available from: 202.204.209.200

  Article: Construction of a recombinant S. cerevisiae expressing a fusion protein and study on the effect of converting xylose and glucose to ethanol.

  Jinxin Zhang, Shen Tian, Yazhen Zhang, Xiushan Yang
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  ABSTRACT: Gene XYL1 from Candida shehatae and gene XYL2 from Pichia stipitis were amplified by polymerase chain reaction (PCR), and the two genes were both placed under the strong promoter of alcohol dehydrogenase (ADH) of plasmid pAD2 to produce the recombinant expression vector pAD2-P12. Because the amplified XYL1 fragment lacks the stop codon UAA, the polypeptide expressed in yeast cells should be a fusion protein, which is a fusion of xylose reductase and xylitol dehydrogenase. Subsequently, the pAD2-P12 vector was transformed into Saccharomyces cerevisiae YS58 to produce a recombinant S. cerevisiae YS58-12. It was indicated that S. cerevisiae YS58-12 has the ability of metabolizing xylose to produce ethanol by fermentation experiment. The result of cofermentation of glucose and xylose by using this recombinant S. cerevisiae YS58-12 showed a relatively satisfactory result. The highest percentage of xylose consumption rate reached 81.3% and the ethanol yield was equal to 67.14% of the ideal value.
  Applied Biochemistry and Biotechnology 09/2008; 150(2):185-92. · 1.94 Impact Factor