热稳定性过氧化氢酶工程菌株发酵条件的研究

Study on Culture Conditions of Engineered Strain of Thermostable Catalase

重组大肠杆菌UM2 1携带来自嗜热脂肪芽孢杆菌过氧化氢酶的基因 ,在以IPTG作为诱导物时 ,在IPTG浓度为 0 75mmol/L、起始 pH6 5、装液量 5 0mL/2 5 0mL三角瓶的条件下 3 7℃诱导 3h ,酶的表达水平最佳 ;在以乳糖作为诱导物时 ,在乳糖质量浓度为 10 g/L、起始 pH7 5、装液量 5 0mL/2 5 0mL三角瓶的条件下 ,3 7℃诱导 5h ,酶的活力最高。乙酸的存在能够抑制酶的表达。工程菌在最适条件下酶活力可达 3 0 0 0 0～ 3 5 0 0 0U/L以上 ,约是原始菌株嗜热脂肪芽孢杆菌的 10倍。工程菌在无选择压力的条件下连续传代 60代 ,基本保持稳定 ,连续传代 10 0代 ,仍有 80 %左右的菌株携带重组质粒。

The recombinant E coli carried catalase gene from Bacillus stearothermophilus  The conditions for expressions of recombinant catalase were reported in this paper For expression of catalase using IPTG (isopropyl β D thiogalactoside) as an inducer, the best conditions were: IPTG concentration, 0 75?mmol/L; inducing time, 3 hours; inducing temperature, 37℃; initial pH, 6 5, broth volume, 50?mL/250?mL flask For expression of catalase using lactose as an inducer, the best conditions were: lactose concentration, 10?g/L; inducing time, 5 hours; inducing temperature, 37℃; initial pH 7 5, broth volume, 50?mL/250?mL flask The recombinant plasmid was stable after cultivation in LB broth at 37℃for 60 generations without antibiotic selection Under optimal conditions, the catalase activity reachs up to 30～35 U/?mL,which is about tenfold that of Bacillus stearothermophilus 