L-arabinose pathway engineering for arabitol-free xylitol production in Candida tropicalis.
Xylose reductase (XR) is a key enzyme in biological xylitol production, and most XRs have broad substrate specificities. During xylitol production from biomass hydrolysate, non-specific XRs can reduce L-arabinose, which is the second-most abundant hemicellulosic sugar, to the undesirable byproduct arabitol, which interferes with xylitol crystallization in downstream processing. To minimize the flux from L-arabinose to arabitol, the L-arabinose-preferring, endogenous XR was replaced by a D-xylose-preferring heterologous XR in Candida tropicalis. Then, Bacillus licheniformis araA and Escherichia coli araB and araD were codon-optimized and expressed functionally in C. tropicalis for the efficient assimilation of L-arabinose. During xylitol fermentation, the control strains BSXDH-3 and KNV converted 9.9 g L-arabinose l(-1) into 9.5 and 8.3 g arabitol l(-1), respectively, whereas the recombinant strain JY consumed 10.5 g L-arabinose l(-1) for cell growth without forming arabitol. Moreover, JY produced xylitol with 42 and 16% higher productivity than BSXDH-3 and KNV, respectively.
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-Gu, Daejeon, Korea.
Byoung Hoon
BH
Yoon
Woo Young
WY
Jeon
Woo Yong
WY
Shim
Jung Hoe
JH
Kim
D001089:Arabinose / Q000737:chemistry / Q000378:metabolism*; D041022:Candida tropicalis / Q000235:genetics / Q000378:metabolism; D015202:Protein Engineering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013402:Sugar Alcohols / Q000737:chemistry; D014993:Xylitol / Q000737:chemistry / Q000378:metabolism*
D013402:Sugar Alcohols; D001089:Arabinose; D014993:Xylitol; C014999:arabitol