A genetic recombinant hEGF producer E.coli JM101 was immobilized in polyurethane foam matrix and a three-phase fluidized-bed bioreactor was used to produce human epidermal growth factor (hEGF).The results indicated th...A genetic recombinant hEGF producer E.coli JM101 was immobilized in polyurethane foam matrix and a three-phase fluidized-bed bioreactor was used to produce human epidermal growth factor (hEGF).The results indicated that polyurethane foam is an adequate immobilization material. With the addition of polyurethane foam matrix, the free cell density, plasmid stability and hEGF productivity were higher than those without the foam matrix, respectively. The two-stage culture of the immobilized cells was further carried out, in which, the first stage was performed in a three-phase fluidized-bed bioreactor for cell growth and the second stage was performed in bubbling bed for product expression. At a dilution rate of 0.2 h -1 , after continuous cultivation for more than 60 h, the free cell density and product expression were maintained relatively stable. The hEGF productivity was still higher than 140 mg·L -1 and the fraction of plasmid-carrying was more than 27%. The hEGF productivity in two-stage process was higher than the batch process.展开更多
Four strains of microorganisms which have activity of chloroacetophenone reduction were screened, in which Saccharomyces cerevisiae B5 showed the highest activity and good stereoselectivity. This strains showed differ...Four strains of microorganisms which have activity of chloroacetophenone reduction were screened, in which Saccharomyces cerevisiae B5 showed the highest activity and good stereoselectivity. This strains showed different activity on the reduction of various substrates in the following order: 2′-chloroacetophenone > 2-chloromethylacetophenone > 4′-chloroacetophenone > 3′-chloroacetophenone > acetophenone. Ethanol is the best cosubstrate and its optimal concentration is 5%.展开更多
文摘A genetic recombinant hEGF producer E.coli JM101 was immobilized in polyurethane foam matrix and a three-phase fluidized-bed bioreactor was used to produce human epidermal growth factor (hEGF).The results indicated that polyurethane foam is an adequate immobilization material. With the addition of polyurethane foam matrix, the free cell density, plasmid stability and hEGF productivity were higher than those without the foam matrix, respectively. The two-stage culture of the immobilized cells was further carried out, in which, the first stage was performed in a three-phase fluidized-bed bioreactor for cell growth and the second stage was performed in bubbling bed for product expression. At a dilution rate of 0.2 h -1 , after continuous cultivation for more than 60 h, the free cell density and product expression were maintained relatively stable. The hEGF productivity was still higher than 140 mg·L -1 and the fraction of plasmid-carrying was more than 27%. The hEGF productivity in two-stage process was higher than the batch process.
文摘Four strains of microorganisms which have activity of chloroacetophenone reduction were screened, in which Saccharomyces cerevisiae B5 showed the highest activity and good stereoselectivity. This strains showed different activity on the reduction of various substrates in the following order: 2′-chloroacetophenone > 2-chloromethylacetophenone > 4′-chloroacetophenone > 3′-chloroacetophenone > acetophenone. Ethanol is the best cosubstrate and its optimal concentration is 5%.
