Xylitol production at high temperature by engineered Kluyveromyces marxianus

Several recombinant Kluyveromyces marxianus strains were constructed through overexpressing the Neurospora crassa xylose reductase genes. YZJ015, which maintained the original xylitol dehydrogenase gene, produced xylitol with the highest productivity (1.49 g L−1 h−1) from 100 g L−1 xylose at 42 °C. Even at 45 °C, YZJ015 was still able to produce 60.03 g L−1 xylitol from 100 g L−1 xylose with a productivity of 1.25 g L−1 h−1. In addition, for 20 rounds of cell recycling at 42 °C, YZJ015 produced 71.35 g L−1 xylitol from 100 g L−1 xylose with a productivity of 4.43 g L−1 h−1 per cycle. YZJ017, in which the xylitol dehydrogenase gene was disrupted, produced 100.02 g L−1 xylitol at a yield of 1.01 g g−1 from 100 g L−1 xylose with 40 g L−1 glycerol as co-substrate at 42 °C. These engineered strains provide an excellent foundation for xylitol production at elevated temperatures.