Fig. 6.

Squalene production by down‐regulation of ERG1 transcription in the chassis SQ3‐4. (A) Down‐regulation of ERG1 transcription of industrial strain by P. rhodozyma ERG1 promoter. (B) Influence of down‐regulating ERG1 transcription on cell growth and squalene content of industrial strain. Yeast cells were cultivated in YPD containing yeast extract YE‐N at 30°C and 200 rpm for 24 h. (C) Squalene production by the engineered strain SQ3‐5 in fed‐batch fermentation in cane molasses medium. Fermentation was conducted in 1‐L bioreactor with cane molasses and ammonium sulphate as the main feedstock. Data are presented as the means of three biological replicates. Error bars represent standard deviations (n = 3). For significance analysis, results of strain SQ3‐4 were used as the controls. Student’s t‐test was used for statistical analysis (***P < 0.001).