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Fig. 2 | Biotechnology for Biofuels and Bioproducts

Fig. 2

From: Metabolic recycling of storage lipids promotes squalene biosynthesis in yeast

Fig. 2

Squalene production in engineered yeast strains. A Construction of squalene-producing strains by multicopy integration of the tHMG1 gene into the SQ00 strain, our platform strain for terpene production. Increasing the tHMG1 copy number (up to 4 copies) comparably increased squalene production. B Changes in the relative mRNA expression level of the tHMG1 gene. The relative expression levels of the tHMG1 gene from the engineered strains were based on the expression level of the tHMG1 gene from the WT strain at 24 h. The copy numbers of the integrated tHMG1 gene is positively correlated with its expression up to 4 copies. C Partial inhibition of Erg1 activity reduced metabolic flux toward ergosterol synthesis to enhance squalene production. When Erg1 was tagged with an N-degron in the SQ4t stain (resulting in the SQ4td strain), degradation of Erg1 successfully redirected metabolic flux toward squalene production. In contrast, although partial inhibition of Erg1 activity with the addition of its inhibitor terbinafine was likely effective for squalene production, a pronounced reduction in squalene production with increasing terbinafine concentration was observed. Yeast cells were grown in shake flasks with YSC minimal medium with 2% (w/v) glucose at 30 °C. All data are presented as the mean ± standard deviation of biological triplicates. WT, wild type. Each plus (+) symbol indicates one copy of the gene integrated into the genome

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