Ethanolic cofermentation with glucose and xylose by the recombinant industrial strain Saccharomyces cerevisiae NAN-127 and the effect of furfural on xylitol production.
ABSTRACT 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.
[show abstract] [hide abstract]
ABSTRACT: Industrial processes of lignocellulosic material have made use of only the hexose component of the cellulose fraction. Pentoses and some minor hexoses present in the hemicellulose fraction, which may represent as much as 40% of lignocellulosic biomass, have in most cases been wasted. The lack of good methods for utilization of hemicellulose sugars is a key obstacle hindering the development of lignocellulose-based ethanol and other biofuels. In this chapter, we focus on the utilization of hemicellulose sugars, the structure of hemicellulose and its hydrolysis, and the biochemistry and process technology involved in their conversion to valuable fuels and chemicals.Advances in biochemical engineering/biotechnology 01/2012; 128:199-224. · 1.64 Impact Factor