副产物乳酸对猪链球菌疫苗株ST171发酵的影响

Effect of the lactic acid by-prodcut on fermentation cultivation of swine streptococcosis vaccine strain(ST171)

为提高猪链球菌(S.suis)疫苗的高密度发酵效果,本研究对S.suis疫苗株(ST171)的发酵过程进行检测,利用外源添加试验研究乳酸对ST171发酵的影响,并通过对发酵工艺的优化减少乳酸的生成。结果表明,ST171发酵液中积累有大量对其生长及活菌数量有不利影响的代谢副产物乳酸。经优化确定ST171发酵的最优工艺参数为:溶氧水平20%,初始葡萄糖浓度10 g/L,残糖浓度1 g/L,最大比生长速率小于0.7 h-1。在优化条件下,发酵过程中乳酸生成量与原工艺相比降低了41.41%,菌体生物量和活菌数量分别提高了70.58%、129.09%,取得了良好的发酵效果。

The fermentation process of swine streptococcosis vaccine strain （ST171） was investigated to improve the efficiency of fermentation to achieve the high cell density cultivation. The optimized conditions were focused on reducing the accumulation of abundant byproduct （lactic acid） in the cultivated broth, which was negatively effected the growth of bacteria and viable concentration in fermentation. Several strategies including dissolved oxygen regulation, suitable concentration of initial glucose and residual glucose in culture medium, and the specific growth rate regulation were applied to reduce the lactic acid producing. As the results, the fermentation parameters of ST171 fermentation were optimized with 20% dissolved oxygen, 1% of initial glucose, 0.1% of residual glucose, less than 0.7 h^[-1]of the maximum growth rate. Under the optimal conditions, the concentration of lactic acid was decreased by 41.41% compared with that under original conditions. Biomass and viable concentration were significantly increased by 70.58% and 129.09%, respectively.