Fig. 5

Engineering GAL80 to modify the GAL-regulation system. A Schematic diagram of the GAL-regulation system and the Snf1 network in S. cerevisiae. B Measurements of the leaky expression in different GAL80-engineered strains using GFP as reporter. Strains CGFP01, CGFP02, CGFP03, CGFP04, CGFP05 and CGFP06 were cultured in YPD, and CGFP06 was also cultured in YPD with addition of 5% galactose. C Measurements of the transcriptional efficiency in different GAL80-engineered strains using GFP as reporter under conditions of different galactose concentrations. D Comparison of the growth state of strain AC24 with or without the addition of 5% galactose. E Comparison of β-amyrin production in the strain AC24 with or without the addition of 5% galactose