| ε-Poly-L-Lysine is comprised of lysine linked by amide bond through microbial fermentation. It has excellent antibacterial activity against Gram-positive and Gram-negative bacteria, yeast and some kinds of viruses. In additional ε-Poly-L-Lysine is soluble and attractive heat stable. At present ε -Poly-L-Lysine have been used as natural food preservative mainly, degradable biological matreria, coat of drug, carrier of target drug and medical research.In the essay Streptomyces albulus was considered as tool of production, in order to improving the productivity of ε-PL. optimizing the process of fermentation, making out the rules of batch fermentation and predicting the secondary structure of ε -PL, works were done as following. (1) morphological and physiological -biochemical characteristics of Streptomyces albulus, and the breeding of the strain producing ε -PL. (2) the optimization of culture media and conditions (3) the effect of stir velocity and pH on the synthesis of E -PL in batch fermentation (4) the prediction of ε-PL's secondary structure and biochemical attributes.AEC and glycine were choose as resistant label, their corresponding concentration was 6mg/mL and 3mg/mL respectively. Meanwhile the elective method of inhibition circle was be used as the second limiting condition during the breed of mutant. Four bacterial species such as Escherichia coli, Bacillus subtilis, Saccharomyces cerevisiae and Lactobacillus were tested, the results showed that Bacillus subtilis was the most sensitive among those microbe.Streptomyces albulus TF-1 was treated by UV and DBS in order. Firstly we studied the effect of UV on the survival rate of cells, then drew a plot of mutation depending on the results. Meanwhile the law about mutation was considered, in according to the above conclusion the optimum irradiation time was 25S. After mutation, initial selection and repeat selection I got a mutant which could produce 0.51g/L.I chose the UV mutant as the initial strain of DES treatment. The effect of the usage and time of DES treatment on the survival rate of cell were studied firstly, the optimum value of usage and time were 1 one percent and 25min. After mutation, initial selection and repeat selection I got a mutant which could produce 0.79g/L.In order to investigate the genetic stability, the mutant was test after five continuous inoculation. The results showed that the mutant could transfer the genetic information to the son generation.Different carbon and nitrogen resource had conspicuous difference in the synthesis of ε -PL, the test indicated that glucose and ammonium sulfate benefited obviously the synthesis of ε -PL. furthermore we studied the function of the mixture of distinctive nitrogen resource. When we blended the yeast extraction to ammonium sulfate, the yield of ε-PL increased obviously. In additional we added various inorganic salts such as K.2HPO4, KH2PO4, MgSO4, ZnSO4 and FeSO4 to investigate the effects. The conclusion told me that except ZnSO4 and FeSCU other three inorganic salts presented limiting promotion. So we determined to select glucose, ammonium sulfate and yeast extraction to conduct the mixture plan with SAS software. The software helped give me the predictive answer which was five percent of glucose, one and half percent of ammonium sulfate, 1 percent of yeast extraction, by the way the optimum results indicated that there was interaction between glucose and ammonium sulfate.We further studied what condition were the best culture conditions. After contrasting test the results showed that there increased in the yield of ε-PL only under the following conditions such as volume of 50mL in 500mL flask, initial pH 6.0, feed inoculation of 8 percent, culture temperature of 30℃.The researches showed that the stir velocity and pH play an important roles in the fermentation of ε-PL in 5L automatic fermentation jar. High stir speed would improve the growth of cells and the synthesis of ε-PL, however over high stir speed could break the mycelium so as to get the cells... |
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