补料分批法高密度培养德氏乳杆菌保加利亚亚种S-1

High cell density culture of Lactobacillus delbeueckii subsp.bulgaricus S-1 in fed-batch fermentation

将补料分批培养法与化学中和法相结合,对乳酸菌进行高密度培养。通过流加不同组分配比的补料液,发现碳源(葡萄糖)和氮源是乳酸菌增殖的限制性底物,并在此基础上确定了补料液的最优碳氮比为5︰7.5(体积比)。通过5 L自控发酵罐的批式补糖实验,对恒速流加、葡萄糖反馈流加和指数流加等3种补糖模式的发酵进程进行了比较。结果表明,3种补料模式都可以使菌体浓度出现不同程度的增加,葡萄糖反馈流加由于保持了发酵过程中较低的残糖浓度,获得了较高的菌体密度,菌体干重达到3.889 g/L,较分批培养提高43.8%。

High cell density culture of lactic acid bacteria is a significant step of the preparation of DVS lactic acid bacteria starter for yoghurt production. To achieve the aim of high cell density cultivation, fed-batch fermentation was applied, companied by chemic neutralization in our experiment. Firstly, glucose and the nitrogen mixture solution were found as the limiting substrate by feeding media which were composed of different ingredient, respectively. Therefore, these components were considered essential and included in the feeding medium for fedbatch cultivation. Subsequently, the optimal ratio of C/N was determined to be 5：7.5 （V：V）. Finally, In the comparison of three kinds of feeding mode for fed-batch operation in 5L fermentor, it was demonstrated that three kinds of feeding mode made cell concentration increase differently, in which glucose feedback feeding with manual adjustment of flow rate can control glucose concentration within a certain lower range , therefore obtaining the maximum cell concentration .With the glucose feedback feeding ,the dry cell weight was up to 3.889g/L,which increased 43.8% over that of batch culture.