玉米秸秆酸解副产物对重组酿酒酵母6508-127发酵的影响

将木质纤维素类生物质如玉米秸秆等用稀酸水解预处理，在半纤维素水解为单糖的同时，水解液中还会产生一些可能对后续发酵有影响的副产物。本实验分别考查了在玉米秸秆稀酸水解液中检测出的乙酸、甲酸、香草醛、糠醛和羟甲基糠醛对重组木糖发酵菌株S. cerevisiae 6508-127生长和发酵的影响。结果表明，甲酸和乙酸对菌体生长的抑制强于乙醇生成，且甲酸的抑制程度远大于乙酸；2g/L香草醛可使菌体生长延滞期明显延长，而在较低浓度（≤1.2g/L）此现象不明显。糠醛在0.5-1.5g/L范围内对菌体生长有抑制作用，但使乙醇得率提高;羟甲基糠醛在0.2g/L浓度存在就使乙醇得率有明显降低，但使生物量得率提高；研究中还发现，糠醛、羟甲基糠醛和香草醛可被S. cerevisiae 6508-127代谢。

The effects of dilute acid hydrolysate by-products of corn stover on ethanol fermentation of xylose-utilising Saccharomyces cerevisiae 6508-127

During the dilute acid pretreatment of lignocellulosic materials such as corn stover, hemicellulose is hydrolyzed into monosaccharides, and meanwhile, toxic by-products are simultaneously generated, which may influence ethanol fermentation thereafter. Studies on the inhibitory effects of the by-products on ethanol fermentation are of practical use for further improvement of ethanol yield from lignocellulosic materials. Five byproducts, including acetic acid, formic acid, vanillin, furfural and 5-hydroxymethylfurfural, were identified to be the main components in the hydrolysate of dilute acid pretreatment of local corn stover, which were added into the medium at different concentrations to study their impacts on the growth and ethanol fermentation of a recombinant xylose-utilizing yeast strain, S. cerevisiae 6508-127. The ethanol production was inhibited by formic acid and acetic acid to a lesser extent than that to the growth, and formic acid was shown to be much more toxic than acetic acid, showing severe inhibitory effects at the concentration ot 1g/L, nati of the concentration for acetic acid which showed remarkably negative effects on ethanol fermentation. Vanillin caused a much longer lag-phase in growth when the concentration was 2g/L, and the lag-phase was not obvious at lower concentrations. At the concentration of 6g/L, vanillin completely inhibited the fermentation as well as the cell growth. 5- Hydroxymethylfurfural was showed to remarkably inhibit ethanol production, but the biomass yield was higher by exogenous addition of 5-Hydroxymethylfurfural than control. Furfural at 0.5 -1.5g/L inhibited the cell growth, but the ethanol yield was higher than that of the control experiment. It was also found that vanillin, furfural and 5-hydroxymethylfurfural could be assimilated and metabolized by S. cerevisiae 6508-127 under the experimental conditions.