The effects of culture conditions on the secretion of human lysozyme by Saccharomyces cerevisiae A2-1-1A.

Abstract

The effects of initial glucose concentrations on the cell growth, glucose usage, and human lysozyme (HLY) secretion under the ENOl promoter were examined in the Saccharomyces cerevisiae strain A2–1–1A harboring a multicopy plasmid. By increasing the initial glucose from 2 % to 10 %, the HLY secretion increased 7 ~ 8 fold although the cell growth was not affected. By adding a mixture of mineral salts to the basal medium, the HLY secretion was increased about twice due to the continuity of the HLY expression at the stationary phase of cell growth.The high HLY secretion (5.5 mg per liter, 47-fold higher than the original level) was achieved by the strain A2–1–1A grown in the synthetic basal medium containing 10% initial glucose, and supplemented with mineral salts containing ammonium sulfate, potassium phosphate, potassium chloride, magnesium sulfate, and iron sulfate.