Studies on Squalene Biosynthesis and the Standardization of Its Extraction Methodology from Saccharomyces cerevisiae

In this study, a homogenization-based extraction method was developed and was compared to five conventional methods of squalene extraction. Squalene recovered from this novel procedure gave 3.5-fold, 10-fold, 16-fold, and 8.1-fold higher yield than standard procedures, viz., saponification with 60% KOH, acidic saponification, saponification with 18% KOH, and glass beads method, respectively. Furthermore, this procedure has been evaluated on laboratory Saccharomyces cerevisiae strains such as BY4742 and CEN.PK2-1C (native), deletion strains (ERG6 and ERG11), and tHMG1 overexpressed S. cerevisiae strains. When sonication method of cell lysis was replaced with homogenization, it was found that the yields were significantly higher and reached a value of 9 mg/g DCW in case of BY4742. In addition, squalene yield in ergosterol mutant strains has been analyzed and was found to be 1.8-fold and 3.4-fold higher in ERG6 and ERG11 deletion strains, respectively, than in BY4742. Squalene was also found to be higher at the optimized temperature of 30 °C and pH 6.0. Furthermore, tolerance of S. cerevisiae to external squalene at various concentrations has been carried and found that the organism was tolerant up to 25 g/L of squalene.