德氏乳杆菌保加利亚亚种培养基及培养条件的优化

为了降低德氏乳杆菌保加利亚亚种的工业生产成本和提高发酵液的菌浓度，通过单因素试验和旋转中心组合设计（central composite design,CCD）相结合的方法优化培养基的组分和培养条件。优化后的培养基成分为:葡萄糖30 g/L、豆粕28 g/L、玉米粉14 g/L、乳清粉28 g/L、K2HPO4 3.0 g/L、柠檬酸三铵2.5 g/L、乙酸钠5 g/L、吐温-80 1.25 mL/L、MgSO4·7H2O 0.2 g/L、MnSO4·4H2O 0.0625 g/L；培养条件为:初始pH值7.1，温度37 ℃，接种量4%（体积分数），静置培养。经优化后活菌数达到 6.07×109 CFU/mL，明显高于原MRS培养基（5.8×108 CFU/mL），且其成本较原MRS培养基的成本降低了4000元/t。

Optimization of Medium Constituents and Fermentation Conditions for Lactobacillus delbrueckii subsp. Bulgaricus

To reduce the costs of L.delbrueckii subsp.Bulgaricus industrial production and increase the CFU number in the fermentation broth,the medium constituents and fermentation conditions were optimized.The culture medium ingredients were optimized by single-factor test and central composite design（CCD ) experiment,and the culture conditions were also optimized by single-factor test based on the above experiment.The ingredients of culture medium were obtained as glucose 30 g/L,bean pulp 28 g/L,corn flour 14 g/L,whey mist 28 g/L,K2HPO4 3.0 g/L,triammonium citrate 2.5 g/L,sodium acetate 5 g/L,Tween-80 1.25 mL/L,MgSO4·7H2O 0.2 g/L,MnSO4·4H2O 0.062 5 g/L,and the culture conditions were initial pH 7.1 of fermentation liquid,temperature of 37 ℃,inoculation amount of 4%（V/V）and stationary culture.After optimizing the number of CFU number was 6.07×109 CFU/mL,significantly higher than the CFU number in the original MRS culture medium (5.8×108 CFU/mL),and the cost was reduced by 4000 yuan/t compared to the original MRS culture medium.