耐酒精高产L-乳酸菌株的筛选及发酵培养基优化

Screening of an Alcohol Tolerant and High-yield L-lactic Acid Strain and Optimization of Culture Medium

为提高L-乳酸产量,降低L-乳酸的生产成本,该研究经过筛选、驯化获得一株耐酒精且高产L-乳酸的菌株鼠李糖乳杆菌AK-0779。使用玉米酒糟代替部分酵母粉作为菌株AK-0779发酵培养基的氮源。在单因素实验基础上,对葡萄糖添加量、酵母粉添加量和玉米酒糟添加量进行三因素三水平响应面优化试验。结果表明,最适发酵培养基为:葡萄糖添加量9.80%,玉米酒糟添加量0.98%,酵母粉添加量1.72%,L-乳酸产量为78.91 g/L,糖酸转换率为80.52%。与酵母粉完全充当氮源产L-乳酸82.36 g/L相比,产量无显著差异,说明玉米酒糟能有效代替部分酵母粉作为发酵培养基的氮源,降低L-乳酸生产成本。

In order to increase the yield of L-lactic acid and reduce the production cost of L-lactic acid,a strain of Lactobacillus rhamnosus AK-0779 with alcohol tolerance and high yield of L-lactic acid was screened and domesticated.Corn distiller's grains were used as the nitrogen source for the fermentation medium of strain AK-0779 instead of part of yeast powder.On the basis of single factor experiments,three factors and three levels response surface optimization experiments were carried out on the addition of glucose,yeast powder and corn distiller's grains.The results showed that the optimal fermentation medium was glucose 9.80%,corn distiller's grains 0.98%,yeast powder 1.72%,L-lactic acid yield 78.91 g/L and sugar acid conversion rate 80.52%.There was no significant difference in the yield of L-lactic acid compared with yeast powder,which was 82.36 g/L,indicating that corn distiller's grains could effectively replace part of yeast powder as the nitrogen source of fermentation medium and reduce the production cost of L-lactic acid.