Abstract: The human serum albumin was prepared by the expression system of CHO cells, which provided a basis for the preparation and function research of HSA and its protein-fusion drugs. Firstly, the recombinant expression plasmid pMH3-HSA was constructed. Then the positive monoclones were screened by finite dilution and Dot Blot. High density amplification culture by 5 L disposable bioreactor was used after suspension domestication, the serum-free medium B001 and F001 were used as basic and flow media, respectively, the fermentation parameters were 55 r/min, DO 20%-40%, pH 6.8-7.4, and Tm 37 ℃. The cell growth status and expression of target protein HSA during fermentation were detected by cell counts, SDS-PAGE, Elisa and Western Blot, and compared with the HSA protein prepared in the Pichia expression system. The results showed that the highly expressed monoclonal CHO cell line containing exogenous HSA gene was successfully constructed and screened, the maximum yield of HSA reached 180 μg /mL in 5 L fed batch disposable bioreacter, and the product of CHO expression system had almost no degradation. In summary, this study indicated that HSA was more suitable for expression in the CHO system, and its advantage of protein integrity was particularly obvious in this system.

Key words: human serum albumin, CHO expression system, high density fermentation