耐酸耐胆盐嗜酸乳杆菌的紫外诱变选育

Enhancement of the Acid and Bile Salt Tolerant Ability of Lactobacillus acidophilus by UV Mutation

通过紫外诱变提高嗜酸乳杆菌的耐酸耐胆盐能力。通过正交试验确定了诱变参数:20 W紫外灯,菌液稀释至OD6000.65左右,照射60 s,照射距离为30.5 cm,此条件的致死率为90.5%。诱变处理后的菌体在模拟人肠道胆汁盐浓度(0.3%)以及pH=2的选择性培养基中处理不同时间后,活菌计数,最终筛选出具有耐胆盐能力显著增强的突变体L.a.abr。在含0.3%胆盐和pH为2的选择性培养基中培养1.5、2.0、2.5 h时的存活率分别为19.57%、10.87%和4.78%,而出发菌株的相应存活率分别为3.68%、1%、0.23%。

The study was designed to enhance the acid and bile salt tolerant ability of Lactobacillus acidophilus by UV mutation. Parameters with a lethal rate 90.5 % for UV mutation determined by orthogonal test were 20 W UV, bacteria was diluted to around OD600 0.65, illuminate at a distance of 30.5 cm for 60 s. The mutant was screened on the selective medium with a simulated human intestinal bile salt concentration of 0.3 % and pH=2. Cell counting was carried out after incubation for different periods. L.caabr was screened out that with an enhanced ability to tolerate high bile salt concentration with a survival rate of 19.57 %, 10.87 % and 4.78 % after incubated for 1.5 h,2.0 h and 2.5 h respectively,while under the same situation, the starter bacteria was 3.68 %, 1% and 0.23 %.