Expanding xylose metabolism in yeast for plant cell wall conversion to biofuels

Sustainable biofuel production from renewable biomass will require the efficient and complete use of all abundant sugars in the plant cell wall. Using the cellulolytic fungus Neurospora crassa as a model, we identified a xylodextrin transport and consumption pathway required for its growth on hemicellulose. Successful reconstitution of this xylodextrin utilization pathway in Saccharomyces cerevisiae revealed that fungal xylose reductases act as xylodextrin reductases, and together with two hydrolases, generate intracellular xylose and xylitol. Xylodextrin consumption using xylodextrin reductases and tandem intracellular hydrolases greatly expands the capacity of yeasts to use plant cell wall-derived sugars, and should be adaptable to increase the efficiency of both first-generation and next-generation biofuel production.