Fig. 3: Manipulation of sterol homeostasis for the production of 24-epi-ergosterol in yeast.

a Scheme of sterol homeostasis for maintaining a balance between sterol acylation (ARE1 and ARE2) and steryl ester hydrolysis (YEH1 and YEH2). LD lipid droplet. b The effect of sterol homeostasis engineering strategies on the production of 24-epi-ergosterol. The sterol acylation pathway (ARE1 and ARE2) and steryl ester hydrolysis pathway (YEH1, YEH2, and TGL1) genes were overexpressed and/or knocked out, and their effects on the production of 24-epi-ergosterol and other late sterols were evaluated both individually and combinatorially. c Comparison of the fed-batch fermentation performance for YQE231, YQE717, and YQE722. Fermentation profiles of cell growth, titer of 24-epi-ergosterol, and titer of late sterols (here defined as the total amount of ergosta-5,7,24(28)-trien-3β-ol, ergosta-5,7,22,24(28)-tetraen-3β-ol, ergosta-5,7-dien-3β-ol, 24-epi-ergosta-5,7-dien-3β-ol, ergosterol, and 24-epi-ergosterol) were obtained by analyzing samples every 4–8 h. b, c Data were presented as mean values ± SD from three independent biological replicates (n = 3). b The circles represent individual data points. Significance (p value) of the titer of total late sterols (red) and 24-epi-ergosterol (black) were evaluated by a two-sided t-test, no significance (n.s.) presents p > 0.05. Source data are provided as a Source Data file.