Earticle

초록

영어

Xylose reductase (XR) is a key enzyme in xylitol production, catalyzing the reduction of D-xylose to xylitol. However, the XRs in most yeast and filamentous fungi have evolved to have broad substrate specificity for efficient reduction of a number of pentoses and hexoses. The promiscuous property of these enzymes could adversely affect the biological production of xylitol. The hemicelluloses, major resources of xylose, also contain abundant L-arabinose and it can be reduced to arabitol, an undesirable byproduct. Arabitol, epimer of xylitol, is difficult to remove, and requires high cost in downstream process. Candida tropicalis XR also have a higher activity for L-arabinose than D-xylose, and this substrate specificity causes the formation of an arabitol byproduct. Neurospora crassa XR (NcXR) has significantly higher activity toward D-xylose than L-arabinose. However, because C. tropicalis and N. crassa have different patterns of codon usage, all NcXR codons were changed into preferred codons in C. tropicalis. In order to change substrate specificity of optimized NcXR (NXRG), point mutations were introduced by site-directed mutagenesis. Expression cassettes harboring mutated NXRGs were integrated into the genome of XYL1-disrupted C. tropicalis.
The resulting recombinant yeasts showed changed substrate specificity toward xylose and arabinose. In xylitol fermentation, they showed lower arabitol/xylitol ratio than that of the parental strain.

키워드

저자

• Byoung Hoon YOON [ Dept. of Biological Sciences, KAIST, Daejeon, Korea. ]
• Woo Young JEON [ Dept. of Biological Sciences, KAIST, Daejeon, Korea. ]
• Woo Yong SHIM [ Dept. of Biological Sciences, KAIST, Daejeon, Korea. ]
• Jung Hoe KIM [ Dept. of Biological Sciences, KAIST, Daejeon, Korea. ]

참고문헌

발행기관

간행물

표지보기 관심저널 등록

• 간행물명

  한국생물공학회 학술대회

• 간기

  반년간

• 수록기간

  1985~2013

• 십진분류

  KDC 476 DDC 576