以高产淀粉的优质红薯品种为原料,采用生产菌株米根霉Fp-6研究不同的红薯预处理方式对高光学纯度L-乳酸发酵的影响,并进行了50 L发酵罐放大试验。结果表明:用制备的红薯淀粉为原料,产酸和发酵周期均与以玉米淀粉为原料相同。当红薯液化液中的有机N含量高于0.25 g/L时,产乳酸量和糖转化率明显下降,副产物富马酸和甘油浓度明显增加,菌体量显著增加。无机N对发酵产酸有促进作用。用去除红薯中部分有机N的液化液进行发酵,在50 L罐中其产乳酸量达91.3 g/L,糖转化率为81.28%,发酵周期48 h。

Taking quality sweet potato varieties with high-yield starch as experimental material,the effects of different pretreatment of sweet potato on fermentations of L-lactic acid with high optical purity by Rhizopus oryzea Fp-6 were studied,and the enlarge tests were carried out in 50 L fermentor. While comparing sweet potato starch to corn starch as experimental material,the results showed that there were no differences on the yield of L-lactic acid and fermentation period. When the concentration of organic N was higher than 0. 25 g / L in the liquefied sweet potato solution,the lactic acid yield and the conversion rate of sugar were decreased significantly,while the biomass and the content of by-products( fumaric acid and glycerol) were increased obviously. However,inorganic N had the role to facilitate lactic acid fermentation. In the fermentation test with the liquefied sweet potato solution which removed a part of organic N,the results showed that the yield of L-lactic acid was 91. 3 g / L,and the conversion rate of sugar was as high as 81. 28%,and the fermentation period was 48 h in 50 L fermentor.