Metabolic engineering strategies for pentose fermentation are developed to fi­nally generate strains that ferment pentose sugars to ethanol under industrial conditions, which may include suboptimal pH and an array of compounds which inhibit cellular metabolism. Industrial strains of S. cerevisiae, including baker’s yeast, generally out-compete most other microorganisms with regard to the properties required in industrial ethanol production [9,10,133-135], including ethanol productivity, ethanol tolerance, lignocellulose hydrolysate tolerance, and tolerance to low pH [136].

5.1