长双歧杆菌的最适底物解析和高密度发酵工艺优化

Optimization of substrate in high-density fermentation of Bifidobacterium longum

为提高长双歧杆菌的培养密度,分别测定了3株菌株在添加不同氮源与微量元素时的生长浓度,确定最适底物,并进一步测定各菌株生长速率被抑制渗透压和生长完全抑制渗透压,通过分析菌株在不同碳氮比、不同浓度微量元素与不同初始渗透压(底物浓度)条件下的最大生物量,确定最优培养工艺。结果表明,长双歧杆菌对酵母类氮源利用率最高,其限制性微量元素是Mg^(2+);底物碳氮比基于菌株生长速率被抑制时碳氮消耗比、底物浓度,基于完全抑制渗透压计算出的理论碳氮消耗量配制培养基时最利于菌体增殖。另外最高生物量与Mg^(2+)浓度在一定范围内呈正相关。以酵母浸粉FM803作为氮源、葡萄糖作为碳源(碳氮质量比为2.5∶1),在最适培养pH(5.00)下分批培养,长双歧杆菌CCFM 687、CCFM 1029和FGSZY 17L7最高活菌数分别达到(7.9±1.1)×10^(9)、(9.3±0.5)×10^(9)和(1.1±0.1)×10^(10) CFU/mL,是MRS培养的50~70倍。该研究结果的应用将显著提高长双歧杆菌的工业化生产效率。

In order to improve biomass yield of Bifidobacterium longum,three strains were determined when different nitrogen sources and trace elements were added to screening the optimum substrate.Furthermore,the osmotic pressure was measured when the growth rate of each strain was inhibited and growth completely inhibited.The results showed that B.longum had the highest utilization rate with yeast nitrogen.The limiting trace element was Mg^(2+).The substrate C/N ratio was based on the C/N consumption ratio when the strain growth rate was inhibited.The substrate concentration was based on the carbon and nitrogen consumption calculated by the theory of complete inhibition of osmotic pressure.In addition,the maximum biomass was positively correlated with Mg^(2+)in a certain range.When yeast extract FM803 was used as nitrogen source and glucose as carbon source(C/N mass ratio 2.5),the viable bacteria numbers of B.longum CCFM 687,CCFM 1029 and FGSZY 17L7 could reach to(7.9±1.1)×10^(9),(9.3±0.5)×10^(9),and(1.1±0.1)×10^(10) CFU/mL,50-70 times higher than that of in MRS.The results will significantly improve the industrial production efficiency of B.longum.