Effect of oxygen enrichment aeration on penicillin G acylase production in high cell density culture of recombinant E. coli
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A strain of E. coli 9633 harboring pGL-5 is employed to develop the process producing penicillin G acylase (PGA). Medium studies show that 0.8% glucose is a proper initial carbon source concentration in the start medium. Whereas, study of nitrogen sources in the production medium exhibits that 2% soybean meat hydrolysate and 0.5% casein hydrolysate give the best result in terms of cell concentration. High cell density culture is carried out through the application of oxygen enrichment aeration (OEA). With the treatment of OEA, the cell concentration and specific PGA activity raise to 2.1 and 1.4 times, respectively, as compared to those without OEA. In a 75 l fermentor, the cell concentration can reach 323 (g wet cell weight/l) with a specific PGA activity of 47 (IU/g w.w.) after 24 h under OEA treatment. This means that the PGA activity of the broth can reach 15 (IU/ml).
KeywordsNitrogen Source Cell Concentration Medium Study Production Medium Casein Hydrolysate
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