| Elastase is a kind of protease that can specially degrade elastin, so it has broad applications in medical therapy, food processing and daily use chemicals industry. In this study, elastase-producing strain was screened and breed. And then the cultivation process and technology of this elastase-producing Bacillus strain were fully discussed. The batch process and dynamics model were determined. Meanwhile the effect of Tween-80 on cell growth and elastase secretion was studied. The purification and characterization of elastase from Bacillus sp. were investigated, and the elastolysis kinetics was basically reported. Finally, the application effect of elastase in meat tenderization and its reaction mechanism were researched.(1) The elastase producing strain was isolated from soil and its activity was 60U/mL cultivation time 24h, and it was identified as Bacillus sp. EL3. Elastase productivity of Bacillus mutant EL314CF10 was improved 2.9 times higher than that of initial strain after mutated by ultraviolet, microwave and diethyl sulfate. Glucose and casein were better carbon and nitrogen source, respectively. The wheat bran and feather flour was alternative for glucose and casein source, respectively. At same time the soybean flour was the next better substitute for casein. The corn steep flour can greatly improve cell growth and elastase production. The orthogonal design was adopted to optimize the concentrations of glucose, casein and corn steep flour. The ANOVA results demonstrated the effect of three factors on elastase production was casein>glucose>corn steep flour. The optimized concentration was 4% glucose, 2% casein and 0.5% corn steep flour. Charge quantity greatly affected elastase production, which demonstrated that the dissolved oxygen is very important for cell growth and elastase produce.(2) Seed medium optimized with response surface methodology (RSM). The result was shown that beef extract and yeast extract were important factors that affect seed growth, peptone and NaCI had no significant effect on seed growth. And the optimal concentration of beef extract and yeast extract was optimized with RSM.The culture medium was optimized with RSM. During the medium development, the two-step optimizations were adopted. The optimized culture medium was(g/L): glucose 74.0, casein 11.30, corn steep flour 6.16, K2HPO42.06, MgSO4-2H2O 0.34, pH7.5. The optimized medium can greatly increase elastase production and cell growth when compared that of the partially optimized medium and/or initialoptimized culture medium. The addition of inorganic salts and bioactive agents and macromolecules polymers significantly affect cell growth and elastase production. The result show that Ca ion can in some extent increase elastase production and cell growth, Tween-80 can improve elastase secretion and bacterial growth, 0.1 % SDS has different effect on cell growth and elastase production, in macromolecules only 0.1% collagen has positive effect on elastase production and bacterial growth. Other polymers have inhibiting effect or litter positive effect on cell growth and elastase production. The completely optimized culture medium can significantly improve elastase production and cell growth, especially for specific production rate.(3) The cultivation conditions were optimized with fractional factorial design (FFD) and central composite design (CCD). It is found that shaking speed and cultivation time have significant effect on elastase produce. The optimized cultivation condition was: shaking speed 220r/min and cultivation time 25h in the flask experiments, the predicted elastase activity was 434U/mL under the optimized culture conditions. The effects of cultivation temperature on cell growth, glucose consumption and elastase production were also investigated. The elastase production at 37℃ was better than that at 35℃; the special cell growth rate at 35℃ was greater than that at 37℃.The addition of elastin in the fermentation medium was studied. The adding of elastin can effectively increase...
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