Abstract: The invention relates to use of a substrate comprising C5 compound-containing material, in the growth of Saccharomyces yeast or the production of a product of Saccharomyces yeast, wherein the C5 compound-containing material is: (a) C5 compound-containing material obtained from lignocellulosic hydrolysate; (b) C5 compound-containing material obtained from fermentation of lignocellulosic hydrolysate; or (c) a mixture of (a) and (b). The invention also relates to a method of producing Saccharomyces yeast biomass or a product of Saccharomyces yeast using the substrate, and to methods of producing ethanol comprising incubating Saccharomyces yeast produced by the use or method. The invention further relates to strains of Saccharomyces yeast suitable for the use or methods.