The sugar available for fermentation after the pretreatment and hydrolysis of biomass can be either
heterogeneous like sucrose and glucose when originated from lignocellulosic biomass. Thus, the main
bulk of biomass used for ethanol production are two types of sugars, the disaccharide sucrose and the
monosugar glucose, both of them can easily be fermented to ethanol by the traditional baker’s yeast, S.
cerevisae.