Impact of Vanilin in Hydrolysate of Corn Stalk on L-lactic Acid Fermentation

Abstract

During the liquid hot water pretreatment of lignocellulosic materials such as corn stalk, hemicellulose is hydrolyzed into monosaccharides, and meanwhile, toxic by-products are simultaneously generated, which may influence L-lactic acid fermentation. Studies on the inhibitory effects of the by-products on L-lactic acid fermentation are of practical use for further improvement of L-lactic acid yield from lignocellulosic materials. In this study, one by-product, vanillin, was identified in the hydrolysate of local corn stalk, which was added into the medium at different concentrations to study their impacts on the growth and L-lactic acid fermentation of a Rhizopus oryzae (AS3.819). The work indicated that L-lactic acid production was inhibited by vanillin to a lesser extent than that to the growth. Vanillin caused a much longer lag-phase in growth when the concentration was 0.8 g/l, which showed remarkably inhibition effect, and the lag-phase was not obvious at lower concentrations. At the concentration of 1 g/l, vanillin completely inhibited the fermentation as well as the cell growth.