Fig. 4.

Effects of single‐gene overexpression of genes involved in the MVA pathway on γ‐bisabolene production. Ten genes including ACOAAT1, ACOAAT2, HMGS, HMGR, MK, PMK, PMVADO, IPPDI, GGPPS and FPPS involved in MVA pathway were overexpressed individually with γ‐bisabolene synthase. Bars represent γ‐bisabolene titers, and lines represent gene expression increase over controls. Titers of γ‐bisabolene were quantified after 5 days of cultivation in shake flasks with 50 ml of liquid YPD medium. The mRNA levels of the ten genes were measured by the SYBR Green I fluorescence method after 3 days of cultivation in shake flasks with 50 ml of liquid YPD medium. Glucose was used as the carbon source. The Po1g KγBS strain cultivated in parallel was used as control, and the gene encoding the β‐actin protein was used as the internal standard. Relative gene expression was calculated relative to β‐actin by 2^{‐▵▵ C T} and normalized to controls. All values presented are the mean of three biological replicates ± standard deviation. *P < 0.05, significantly different from control by ANOVA.