원문정보
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영어
Hepatitis B virus causing the chronic diseases of the liver is surrounded by envelop proteins. Their major component is the small hepatitis B surface antigen (sHBsAg).1) A plasmid containing the sHBsAg gene under the Gal promoter and MFα signal sequence was constructed for the chromosomal integration and expression of the sHBsAg gene in recombinant S. cerevisiae. Batch fermentation of S. cerevisiae 2805/Mδα _sHBsAg with 20 g/L glucose and 30 g/L galactose resulted in 2.21 mg/L of sHBsAg concentration. Appearance of three different sizes of sHBsAg with 25, 35 and 40 kDa indicated that sHBsAg was as three types of authentic, MFα containing and N-glycosylated MFα containing sHBsAg. To improve the expression level of sHBsAg, the PDI1 gene was episomally co-expressed. Batch fermentation of S. cerevisiae 2805/Mδα_sHBsAg_Pdi1 resulted in 9.75 g/L of dry cell mass and 13.3 mg/L of sHBsAg
concentration. Modulation of galactose addition yielded the optimal initial galactose concentration of 15 g/L. Finally, 14.2 mg/L of sHBsAg concentration was obtained in batch fermentation using 20 g/L glucose and 15 g/L galactose, which was 6.5 times higher than that for S. cerevisiae
2805/Mδα_sHBsAg.