Squalene Production using Saccharomyces cerevisiae

Abstract

Squalene is a valuable natural substance found in nearly all organisms, and can be produced by the yeast Saccharomyces cerevisiae. The key regulatory enzyme in squalene biosynthesis is 3-hydroxy-3-methylglutaryl-coenzyme-A (HMG-CoA) reductase (Hmg1). To overcome further down regulation of Hmg1, a truncated Hmg1 (tHmg1), an enzyme which has the catalytic domain of the Hmg1 only, and is not regulated by intermediates, was overexpressed instead of the original enzyme. Because of its strong and fast glycolysis, S. cerevisiae converts substantial portions of glucose into ethanol rather than into the squalene. In order to overcome this problem, the slower glucose assimilating S. cerevisiae (SK2) was employed for the overexpression of the tHmg1 enzyme. Accumulated squalene in the SK2 cells were extracted by using the alcohol/KOH method. The SK2 strain with the overexpression of tHMG1 produced about 30 times more squalene than the strain without the tHMG1. Additionally, the Methanol/KOH combination for squalene extraction showed better squalene recovery than ethanol/KOH combination.