Fermentation Condition Optimization Of Saccharomyces Cerevisiae For Synthesizing Dammarendiol And Its Intermediate Metabolites

Squalene, 2,3-oxidosqualene and dammarenediol are important medical industrial intermediates, also precursors of terpenoids by Saccharomyces cerevisiae. But up to now, production of squalene, 2,3-oxidosqualene and dammarendiol are not enough for application demands. So, a further optimization of fermentation condition is desperately needed to improve the production.S. cerevisiae gene engineering strains W303-tHMGR, W303-tHMGR-ERG1, W303-tHMGR-ERG20, W303-tHMGR-ERG1-DS were selected. Squalene, 2,3-oxidosqualene and dammarenediol were key intermediate metabolites to compare wild-type and engineering strains. This paper completed single factor optimization, climbing experiment, Box-Behnken experiment, orthogonal experiment, 5L fermentor level of batch fermentation and fed batch fermentation, the fermentation dynamics simulation. The main results were as follows:1) Testing intermediate metabolites of tHMGR, ERG1 and ERG20 to S.cerevisiae. When genes reinforced, squalene and 2,3-oxidosqualene synthesis had varying degrees of increase. Squalene and 2,3-oxidosqualene of W303-tHMGR-ERG1 reached 33.13mg/L and 2.16mg/L, 73.3 and 1.8 times of the original one.2) Strains W303-tHMGR-ERG1, W303-tHMGR-ERG1-DS were selected. Through response surface optimization and orthogonal optimization, culture conditions were optimized. Yield of 2,3-oxidosqualene was 95.72 mg/L, 71.7% higher than initial output, dammarenediol yield was 77.45 mg/L, 16.2 times than initial production.3) Strain W303-tHMGR-ERG1-DS was selected to finish the 5L fermentater experiment. In the 5L fermentater, concentration of dammarendiol reached 75.47 mg/L, which is 16.8 times of the initial conditions. In 36 h we added carbon source, nitrogen source, finally in 5 L fermenter dammarendiol yield reached 105.87 mg/L, 23.5 times of the initial conditions. Through building batch fermentation kinetics model, revealed the process of substrate consumption, bacteria growth and dammarendiol synthesis.