以废弃毕赤酵母为高效氮源强化丁酸发酵生产

为有效利用固态废弃毕赤酵母,高效发酵生产丁酸,建立了以80 g/L玉米淀粉为基础培养基、以废弃毕赤酵母处理液为高效有机氮源,连续补加葡萄糖的丁酸发酵工艺。7 L厌氧发酵罐下,发酵20h,先以1∶4的比例添加250~400 g/L规格的废弃酵母处理液替代昂贵的发酵用复合培养基,再连续补加葡萄糖浓缩液。最终的丁酸质量浓度为45 g/L、得率为40%,丁酸占总酸的比率(butyric acid ratio over total organic acids,B/TA)≥0.90的较高水平。该工艺可以有效地利用来自于废弃酵母处理液中的氨基酸,提高细胞生长速度和浓度,增强丁酸合成所依赖的NADH再生速度,间接改善了丁酸发酵性能。与此同时,实现了废弃生物质的有效利用和资源化。

Enhanced butyrate production using waste Pichia pastoris as the efficient nitrogen source

In this study,aiming at effectively utilizing solid waste Pichia pastoris and efficiently producing butyric acid,a novel butyric acid fermentation strategy was developed with 80 g/L corn-starch as the base medium and the pretreated waste yeast suspension as the efficient organic nitrogen source together with consecutive concentrated glucose solution feeding.In a 7L anaerobic fermentor,the waste yeast suspension(250-400g/L specification)was added into fermentation broth with a volume ratio of 1∶4 around 20 h to replace the expensive complex fermentation medium,followed by consecutively feeding concentrated glucose solution.With this strategy,butyric acid concentration,yield and butyric acid ratio over total organic acids(B/TA)reached high levels of 45 g/L,0.40 and 0.90,respectively.This operation strategy could effectively utilize amino acids(4g/L)originated from the waste yeast suspension to increase Clostridium tyrobutyricum growth rate and concentration,enhance butyric acid synthesis dependent NADH regeneration rate under high SO4^2-concentration environment created by waste yeast suspension addition.As a result,butyric acid fermentation performance was indirectly improved,at the same time bio-waste utilization/recirculation was realized.