gTME for Construction of Recombinant Yeast Co-fermenting Xylose and Glucose

Global transcription machinery engineering (gTME) was employed to engineer xylose metabolism. Mutation of the transcription factor gene Spt15 was introduced by error-prone PCR, followed by screening on media using xylose as the sole carbon source. One recombinant strain growing well on such media was chosen for further research. This strain showed modest growth rates in the media containing 50 g/L xylose or glucose at the condition of 30°C, 200 rpm, 96 h, 94.0% and 98.9% of xylose and glucose were consumed, with the ethanol yield were 32.4% and 31.6%, respectively. The control strain had the ethanol yield of 44.3% under the glucose concentration of 50 g/L. When the carbon source was 50 g/L glucose/xylose (1:1), the utilization ratio of xylose and glucose was 91.7% and 85.9%, with the ethanol yield was 26%. Xylose was eventually exhausted. Concentration of the by-product xylitol was very low.