BACKGROUNDThe effect of the combination of acetic acid, furfural and 5-hydroxymethylfurfural on 2, 3-butanediol fermentation of Klebsiella oxytoca was studied by statistical analysis. The compounds were selected taking into account their concentration in the hydrolysate from the acid pretreatment of biomass and their toxicity. A central composite design was used to investigate the influences of these compounds on 2, 3-butanediol yield and biomass formation. RESULTSTwo models were developed to describe the effect of the combination of acetic acid, furfural and 5-hydroxymethylfurfural on biomass and product yield in 2, 3-butanediol fermentation. The proposed model is suited to fit experimental data and to simulate cell growth and 2, 3-butanediol yield, which was confirmed by 2, 3-butanediol production using real hydrolysate as substrate. CONCLUSIONBiomass yield was affected mainly by the main effects' of the tested compounds and no interaction relationship among acetic acid, furfural and HMF was found. 2, 3-butanediol yield was more sensitive to acetic acid concentration. Selective removal of furfural in hydrolysate would contribute to the simultaneous improvement of 2, 3-butanediol yield and cell growth. (c) 2013 Society of Chemical Industry