为提高发酵乳杆菌的增殖浓度,对其高密度发酵培养基成分及培养工艺进行优化以提高其活菌数。结果表明,酵母粉复合大分子肽的蛋白胨是发酵乳杆菌的最适氮源,缓冲盐在恒pH培养时对菌株生长无促进作用,Mn2+和Mg2+均是发酵乳杆菌的限制性微量元素。另外,中性条件下酸根的积累不会对发酵乳杆菌有特异性毒害作用,其生长主要是受到渗透压的抑制。以菌株生长速率被抑制时的碳氮消耗比作为培养基中的碳氮源比例,基于菌株生长速率被抑制时的渗透压确定碳氮源的添加量。进一步优化恒pH分批培养和恒pH自动反馈补糖培养工艺,得到各菌株的最优培养策略:发酵乳杆菌FXJCJ6-1、发酵乳杆菌FGDLZR161、发酵乳杆菌CCFM422分别在恒pH 6.0、5.5、5.5分批培养时,活菌数分别达到(1.3±0.1)×1010、(1.1±0.1)×1010、(9.5±0.5)×109CFU/mL,较在MRS培养基静置培养时的活菌数提高了3.1、3.8和4.6倍。该研究结果的应用将显著提高发酵乳杆菌的工业化生产效率。
In order to increase the proliferation concentration of Lactobacillus fermentum, the high-density fermentation medium composition and cultivation technology were optimized to increase the number of viable counts. The results showed that peptone of yeast powder composite macromolecular peptide was the most suitable nitrogen source for L. fermentum, and saline buffer had no effect on the growth of the strain during constant pH culture. Both Mn2+ and Mg2+ were the limiting trace elements of L. fermentum. In addition, the accumulation of acid anions under neutral conditions did not have specific toxic effects on L. fermentum, and the growth of L. fermentum was mainly inhibited by osmotic pressure. The carbon-nitrogen consumption ratio when the growth rate was inhibited was used as the ratio of the carbon and nitrogen source in the medium, and the concentration of the carbon and nitrogen source was determined based on the osmotic pressure when the growth rate of the strain was inhibited. The constant pH batch cultivation and constant pH automatic feedback sugar supplement cultivation process to obtain the optimal cultivation strategy for each strain were further optimized: L. fermentum FXJCJ6-1, L. fermentum FGDLZR161, L. fermentum CCFM422 at constant pH 6.0, 5.5, 5.5, respectively. In batch culture, the number of viable counts reached (1.3±0.1)×1010, (1.1±0.1)×1010 and (9.5±0.5)×109 CFU/mL, respectively. Compared with MRS static culture, the number of viable counts increased by 3.1, 3.8 and 4.6 times, respectively. The application of the research results would significantly improve the industrial production efficiency of L. fermentum.
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