重组大肠杆菌产尿素酶B高密度发酵条件的优化

探究重组大肠杆菌产尿素酶B（urease B subunit, UreB）的高密度发酵条件。通过实验室摇瓶和30 L发酵罐对UreB基因工程菌的发酵条件进行优化。结果表明：30 L发酵罐中以TB培养基为发酵培养基,接种量为5%,发酵温度为37 ℃,pH为6.8,溶氧量为30%左右,培养至2 h开始恒速流加50%甘油,4 h流加50%酵母提取物和50%胰蛋白胨,并加入终浓度为0.5 mmol/L的异丙基β-D-硫代半乳糖苷（isopropyl β-D-thiogalactoside,IPTG),诱导表达4 h,结束发酵,所得菌体干物质约为25.7 g/L,UreB表达量为31.4%。此工艺可以提高UreB的产量。

Optimization of high density fermentation conditions for UreB production from recombinant Escherichia coli

To explore the high density fermentation conditions of recombinant E.coli strain for expression of urease B subunit (UreB), the recombinant Escherichia coli BL21 (DE3) expressing virulence protein UreB was used for fermentation in 30-liter fermenter. Results indicated that: TB medium was used as the basal medium, the inoculation size was 5%, fermentation temperature was 37 °C, the pH was 6.8, the dissolved oxygen content was about 30%, 50% glycerol was added at a constant speed after fermentation for 2 h, 50% yeast extract and 50% tryptone were added at 4 h, then, IPTG with a final concentration of 0.5 mmol/L was added followed by incubation for 4 h.The dry weight of recombinant E.coli and expression rate of UreB reached 25.7g/L and 31.4%, respectively. Our results demonstrated that this process increases the yield of UreB.