为了获得较高酶活力的嗜酸乳杆菌细胞壁蛋白酶(CEP),对嗜酸乳杆菌CEP的提取方法进行优化。经过比较超声波破碎法、Ca2+-free法、溶菌酶裂解3种方法,确认溶菌酶裂解法结合使用非离子清洁剂破壁是提取嗜酸乳杆菌CEP的最佳方法。在单因素试验的基础上,采用正交试验对嗜酸乳杆菌CEP的提取工艺进行优化,得出嗜酸乳杆菌CEP的最佳提取方法:用裂解液(50mmol/L Tris-HCl、100mmol/L NaCl、TritonX-100添加量1%、1.5mg/mL溶菌酶,pH 7.8)悬浮菌体(20mL/g),37℃保温3h,4℃、4500r/min离心20min,取上清液。溶菌酶裂解法提取CEP过程中各因素对CEP提取效果的影响依次为:溶菌酶质量浓度〉裂解pH值〉TirtonX-100添加量〉保温时间。
In this study,the extraction of cell-envelope proteinase(CEP) from Lactobacillus acidophilus was optimized.A comparison of ultrasonic treatment,Ca2+-free treatment and lysozyme lysis for their effectiveness in Lactobacillus acidophilus cell disruption was performed to determine lysozyme lysis as the best method among the three.Further,process conditions optimization for CEP extraction from Lactobacillus acidophilus by lysozyme lysis was carried out using orthogonal array design based on one-factor-at-a-time experiments.The best extraction results were obtained by 3 h incubation at 37 ℃ of Lactobacillus acidophilus cells in pH 7.8 lysozyme lysis buffer containing 50 mmol/L Tris-HCl,100 mmol/L NaCl,1% TritonX-100 and 1.5 mg/mL lysozyme and then centrifugation at 4500 r/min and 4 ℃ for 20 min,and the resulting supernatant was collected as CEP.In addition,lysozyme concentration had the largest impact on extraction efficiency of CEP followed by pH,Tirton X-100 concentration and incubation time.