Optimization of Douchi fibrinolytic enzyme production by statistical experimental methods

Thrombus disease, one of the common cardiovascular diseases, has attracted worldwide attention for its rising mortality and morbidity. Due to the distinct shortages of current fibrinolytic drugs, new fibrinolytic agents warrant investigation. In this study, 8 fibrinolytic enzyme-producing strains were isolated from Douchi-a traditional Chinese food, and strain XY-1 which produced the largest amount of the enzyme was chosen for the following experiments. The enzyme produced by strain XY-1 was named Douchi fibrinolytic enzyme (DFE). We optimized the liquid culture medium of strain XY-1 for enzyme production using Plackett-Burman and Box-Behnken design. The predicted maximal DFE yield was 19.78 FU/mL with 11.4g/L peptone, 0.5g/L magnesium sulfate and 1g/L sodium chloride. How- ever, we acquired maximal production of 21.33 FU/mL in actual experiments, equal to 107.84% of the theoretical value, and the yield had been increased by 79.55% as compared to the yield of un-optimized culture. It was demonstrated that the combined use of Plackett-Burman design and response surface methodology in fermentation optimization can effectively and rapidly increase DFE production.     

二氧化氯、次氯酸钠及其联合消毒模拟水样效果的比较

目的比较不同剂量二氧化氯(ClO2)、次氯酸钠(NaClO)及其联合(ClO2+NaClO)消毒模拟水样的效果。方法以实验室配制含大肠杆菌5.0×104~5.0×105cfu/100ml的模拟水样为研究对象,应用不同剂量ClO2、NaClO、ClO2+NaClO进行消毒试验,分别消毒60、60、30+60min后,以滤膜法和电位滴定法检测并比较模拟水样中大肠杆菌的杀灭率、ClO2残留量、ClO-2生成量和总余氯量。结果0.4mg/L ClO2、0.5mg/L NaClO,ClO2+NaClO联合配比为0.1mg/L+0.3mg/L或0.2mg/L+0.2mg/L时,为消毒模拟水样的最低有效剂量;与ClO2、NaClO各自单独消毒相比,在ClO2+NaClO联合消毒的模拟水样中,ClO2的残留量增加13.43%~166.67%,ClO2-的生成减小13.11%~19.97%,总余氯量增加9.34%~40.15%。结论二氧化氯、次氯酸钠二者联合消毒饮用水既可提高消毒效果,又可减少消毒剂使用剂量及消毒副产物的生成量。