摘要
Abstract
Medium ingredients for neutral proteinase(NPR) production of B.subtilis CNMC-0014 was optimized using stastically-based experimental designs. A single-factor experiment(SFE) method was adopted to choose the carbon and nitrogen sources significantly influcing NPR biosynthesis. Among the six variables of carbon sources we studied, the most significant variables were stastically elucidated for optimization, and included glycerol and corn flour with the corresponding value of NPR of 3955.16±2.15 U/ml and 3939.15±1.87 U/ml. For nitrogen sources, the most significant variable affecting NPR production was soybean flour with maximun NPR production of 4318.12±5.66 U/ml. The optimum concentration of each significant variable was then determined by range analysis (RA) and analysis of variance (ANOVA), the optimun values for the critical nutrients supplements for the maximun NPR production were 2% of corn flour, 1% of glycerol, 3% of soybean flour and 3% of bran, with the maximun NPR activity of 4526.28 U/ml. Results, statistically, indicated that the influences of clycerol and corn flour on NPR prodoction were significant at 5 % (p＜0.05) level, but, the effect of soybean flour was most significant at 1 % (p＜0.01) and bran had no significant influence (p＞0.05) on NPR production. And meanwhile, the effects of metal ions, dissoluble oxygen (DO), initial pH, strain ages and inoculum sizes on NPR production were also investigated. Resulsts shown that Ca2+, Mg2+, Na+, Zn+, Mn2+ could activate enzyme biosynthesis at different levels, especially Ca2+ with a maximun activity of 4552.97 U/ml. And whenas, Fe3+, Fe2+, K+, Ag+ had strongly inhibitory influence on NPR production, particularly Ag+ (NPR activity was only 987.46 U/ml).The most suitable filled amount of SmF medium in 300 ml Erlenmeyer flask was 50 ml. Optimal pH was 7.5, the most suitable strain ages and inoculum sizes for maximun NPR production were 24-h-old strain and 3% culture broth, respectively.关键词
中性蛋白酶/枯草芽孢杆菌/沉没发酵/单因素试验/正交试验/极差分析Key words
neutral proteinase (NPR)/B. subtilis/submerged fermentation (SmF)/single-factor experiment(SFE),analysis of variance(ANOVA)/range analysis(RA)分类
生物科学
