【摘要】 讨论了大肠杆菌 L -天冬酰胺酶发酵液酶活力的影响因素 ,筛选了大肠杆菌产酶的优化条件 .发现了发酵液酶活力的最适 p H随缓冲介质的变化而变化 ;甘氨酸介质中 ,p H 6 .5 0～ 9.5 0均适于酶活测定 ,且 p H 8.0 0时酶活最高 ;硼酸、Tris、磷酸介质中 ,在 p H 8.5 0时 ,酶活力依次下降 ;酶反应的适宜温度 4 0～ 5 0℃ .对菌株培养的研究表明 ,葡萄糖对产酶有抑制作用 ,适当提高摇床转速可使发酵液酶活力由原来的 136 U /m L增至 14 5 U /m L .在确定的最优培养条件 37℃ ,p H 7.0 0 ,2 5 0 r/min下 ,产酶稳定期可持续 12 h.更多还原

【Abstract】 Influential factors of enzyme activity in fermentation liquid of E.col i L asparaginase are discussed and the optimal L asparaginase production conditions from E.coli are selected. It is found that the optimum pH of the enzymatic reaction in fermentation liquid varies with different buffering medium. In glycin medium, the suitable pH for enzyme activity determination is 6.50~9.50 and maxium activity can be obtained at pH 8.00. In boric acid, Tris, phosphorous acid, the optimum pH is 8.50 and at this pH, enzyme activity reduces successively. The suitable temperature of the enzymatic reaction is 40~50 ℃. The study of strain cultivation shows that enzyme production is inhibited by glucose, the enzyme activity in fermentation liquid can be raised from 136 U/mL to 145 U/mL by properly increasing rotate speed of shaking table. Under the determinate optimal condition 37 ℃, pH 7.00, 250 r/min, the stationary phase of enzyme production can last for 12 h.更多还原