Control of gene expression from the SUC2 promoter of Saccharomyces cerevisiae with the aid of a glucose analyser

A Saccharomyces cerevisiae strain harbouring the recombinant plasmid pSMF38TMA was cultured in a jar fermentor under the control of glucose concentration. In the recombinant plasmid, the mouse alpha -amylase gene was fused to the S. cerevisiae SUC2 promoter. When glucose concentration in the medium was controlled at 10 g/l, the gene expression was completely repressed. On the other hand, the alpha -amylase was produced and secreted in the medium at a very high level, around 200 mg/l as evaluated from the specific activity of commercially available human salivary amylase, when the glucose was kept at 0.15 g/l. This amount was almost 20-fold that obtained at 10 g/l glucose.