Ethanolic cofermentation with glucose and xylose by the recombinant industrial strain Saccharomyces cerevisiae NAN-127 and the effect of furfural on xylitol production.

Saccharomyces cerevisiae strain NAN-127 (2n, prototroph), which contains the xylose reductase-xylitol dehydrogenase (XR-XDH) xylose metabolic pathway was used for the cofermentation of glucose and xylose. Oxygen supply was the most important factor for xylose fermentation and pH 4.5 and a ventilation rate of 0.04 vvm were optimal. The xylose utilization ratio reached 0.655 at an initial xylose concentration of 50 gL(-1) and was 0.9 at an initial concentration of 20 gL(-1). Addition of furfural at late logarithmic phase as electron acceptor to a final concentration of 3.0 gL(-1) decreased the xylitol yield by 17% under micro-aeration conditions without inhibiting cell growth, but also without an increase in ethanol yield. The results are important to the application of strain NAN-127 in the lignocellulosic ethanol process.