5L发酵罐高密度培养番茄红素工程菌及其发酵条件优化

本研究对产番茄红素的工程菌W-05进行发酵条件优化。首先单因素实验确定培养基种类;培养温度;培养基中的较优碳源、氮源以及无机盐。然后根据单因素实验结果,设置响应面实验确定各因素之间的交互影响,响应面实验结果表明培养基各组分为:蛋白胨10.00 g/L、酵母浸出粉5.00 g/L、甘油7.80 mL/L、硝酸铵3.30 g/L、KH2PO4 1.80 g/L、NaCl 11.62 g/L时,番茄红素得率达理论值为3.42 mg/L。在5 L发酵罐中,使用优化后的培养基高密度培养工程菌W-05。实验结果显示工程菌W-05高密度培养较优发酵条件为:p H值为7.0,溶氧百分数为20%左右及指数流加补料。此条件对比普通分批培养条件,菌体的生物量和番茄红素产量显著提高(p<0.05)。优化发酵29 h后的菌体干重达到16.55 g/L,番茄红素得率为19.93 mg/L。这说明改善培养基成分及发酵条件能大幅提高工程菌的番茄红素得率。

High-density Cultivation of Lycopene-producing Engineered Bacteria in 5 L Fermenter and Optimization of Fermentation Conditions

In this study, the fermentation conditions of lycopene-producing engineered Bacteria W-05 were optimized. Firstly, single factor experiments were used to determine the type of culture medium, culture temperature, preferred sources of carbon and nitrogen, and inorganic salt. Then, according to the results of the single factor experiments, the response surface experiments were set up to determine the interaction between various factors. The results of the response surface experiments showed the components of the medium: peptone 10.00 g/L, yeast extract powder 5.00 g/L, glycerol 7.80 mL/L, ammonium nitrate 3.30 g/L, KH2PO4 1.80 g/L, and NaCl 11.62 g/L, under which, the lycopene yield reached a theoretical value of 3.42 mg/L. W-05 was then cultured at a high density using the optimized medium in a 5 L fermenter, and the experimental results showed the optimal fermentation conditions: pH 7.0, dissolved oxygen percentage about 20%, and the use of exponential fed-batch strategy. Under these conditions, the biomass and lycopene production of W-05 increased significantly (p<0.05), compared with those obtained via batch fermentation. The dry weight of bacterial cells reached 16.55 g/L and lycopene yield reached 19.93 mg/L after the optimized fermentation for 29 h. These results show that improving the medium composition and fermentation conditions can greatly increase the yield of lycopene produced by engineered bacterium W-05.