EFFECT OF MEDIA COMPOSITION ON GROWTH, PLASMID STABILITY AND OVINE INTERFERON-TAU PRODUCTION IN SACCHAROMYCES-CEREVISIAE

Recombinant protein production is often influenced by the stability of plasmid carrying the cloned gene and the final biomass yield. Ovine ( sheep) interferon-tau (oIFN tau) has been expressed in Saccharomyces c erevisiae under the regulation of a hybrid alcohol dehydrogenase 2/gly ceraldehyde-3-phosphate dehydrogenase promoter. The influence of media composition on growth rate, biomass yield, plasmid stability and oIFN tau were studied. In a selective medium, with leucine and uracil sele ction, the plasmid stability was good but the yeast failed to grow to high cell densities. In 60-l fermentations, oIFN tau yields of 49 mg/l were achieved for complex media and about 3.4 mg/l for casamino acids with uracil selection based on bioassay. A fraction of the protein wa s insoluble and was solubilized by 6 M guanidine hydrochloride.