earticle

영어

NAD(P)H dependent xylose reductase (XR) - encoded by the yeast KmXYL1 gene - is the key enzyme which facilitates reduction of xylose to xylitol. Multi-copy integration of a mutant KmXYL1 (mKmXYL1) gene was carried out using thermotolerant yeast Kluyveromyces marxianus KCTC17555ΔURA3, in order to enhance xylitol production. The engineered strain (K. marxianus 17555-JBP2) exhibited 440% higher xylitol production than the parental strain at 30°C. Due to a multi-copy integration of the mKmXYL1 gene, various additional differences between K. marxianus 17555-JBP2 and the parental strain were observed, including a 66% increase in NAD(P)H dependent XR activity at high temperature (45°C). Quantitative real-time PCR and transcriptome analysis demonstrated that, relative to the parent strain, K. marxianus 17555-JBP2 exhibited a 3.00-fold higher mKmXYL1 gene copy number and a 9.63-fold elevation in transcription of NAD(P)H dependent XR. After optimization of bioreactor fermentation conditions (agitation speed), high-temperature (40°C) xylitol productivity of K. marxianus 17555-JBP2 exhibited an 81% improvement relative to the parental strain.