title: Effect of heterologous xylose transporter expression in Candida tropicalis on xylitol production rate.
abstract: Xylose utilization is inhibited by glucose uptake in xylose-assimilating yeasts, including Candida tropicalis, resulting in limitation of xylose uptake during the fermentation of glucose/xylose mixtures. In this study, a heterologous xylose transporter gene (At5g17010) from Arabidopsis thaliana was selected because of its high affinity for xylose and was codon-optimized for functional expression in C. tropicalis. The codon-optimized gene was placed under the control of the GAPDH promoter and was integrated into the genome of C. tropicalis strain LXU1 which is xyl2-disrupted and NXRG (codon-optimized Neurospora crassa xylose reductase) introduced. The xylose uptake rate was increased by 37-73 % in the transporter expression-enhanced strains depending on the glucose/xylose mixture ratio. The recombinant strain LXT2 in 500-mL flask culture using glucose/xylose mixtures showed a xylose uptake rate that was 29 % higher and a xylitol volumetric productivity (1.14 g/L/h) that was 25 % higher than the corresponding rates for control strain LXU1. Membrane protein extraction and Western blot analysis confirmed the successful heterologous expression and membrane localization of the xylose transporter in C. tropicalis.
authors: Biotechnology Process Engineering Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 125 Gwahangno, Yuseong-gu, Daejeon, 305-806, Korea.
authors: Woo Young
authors: WY
authors: Jeon
authors: Woo Yong
authors: WY
authors: Shim
authors: Sung Hyeon
authors: SH
authors: Lee
authors: Joon Ho
authors: JH
authors: Choi
authors: Jung Hoe
authors: JH
authors: Kim
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000096:biosynthesis* / Q000235:genetics; D041022:Candida tropicalis / Q000201:enzymology* / Q000235:genetics; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis* / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D014993:Xylitol / Q000096:biosynthesis* / Q000235:genetics; D014994:Xylose / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D009004:Monosaccharide Transport Proteins; D011994:Recombinant Proteins; D014994:Xylose; D014993:Xylitol