Enhancement of Alpha 1-antitrypsin Production in Pichia pastoris by Designing and Optimizing Medium Using Elemental Analysis

Background: Human alpha 1-antitrypsin (AAT) is a monomeric glycosylated protein; it is the potent inhibitor of a whole range of serine proteases and protects tissues against their destructive effects. The human plasma-derived AAT, which is currently used to augment the AAT level in patients, is limited due to high cost and source limitation. Recombinant production of AAT can be considered as a potential alternative. Objectives: This study aims to develop and optimize a new chemically defined medium based on an elemental analysis of the yeast Pichia pastoris for an efficient culture of the recombinant yeast-producing secretory AAT. Material and Methods:An elemental analysis of Carbon (C), Hydrogen (H), Nitrogen (N), Sulfur (S); CHNS in its abbreviated form, and metallic elements was performed to determine the exact molecular constituent of the P. pastoris. The medium components were selected according to the obtained formula; they were optimized by the response surface methodology (RSM). The grown yeast cell was measured at the end of 18 h glycerol batch culture. The amounts of AAT production and elastase inhibitory capacity (EIC) were measured at the end of three days’ methanol feeding. Results: The optimized medium compositions consist of glycerol (40 g.L-1), KH2PO4 (24.78 g.L-1), NaCl, (0.88 g.L-1), MgSO4.7H2O (1.95 g.L-1), (NH4)2SO4 (22.76 g.L-1), and trace elements (20 mL.L-1). The presented quadratic models show that KH2PO4 and (NH4)2SO4, are the most abundant ones in the P. pastoris biomass and have the greatest effect on the cell growth, EIC, and AAT protein production responses. Conclusions: According to the results of this study, it can be concluded that the characterizing cell composition formula could be considered as an appropriate method to design culture media in order to improve cell growth and productivity. Compared to the common P. pastoris chemically defined media, FM22 and BSM, production of AAT protein increased by 1.5 and 1.4 times, respectively, in this new medium.