ARTICLE pubs.acs.org/JAFC
Enhanced Squalene Production by Wild-Type Saccharomyces cerevisiae Strains Using Safe Chemical Means Eleni Naziri, Fani Mantzouridou, and Maria Z. Tsimidou* Laboratory of Food Chemistry and Technology, School of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
bS Supporting Information ABSTRACT: Interest is increasing in establishing renewable sources for squalene, a functional lipid, as the conventional ones are limited. In the present study, squalene production was achieved in a wild-type laboratory Saccharomyces cerevisiae strain by two safe chemical means using terbinafine (0.050.55 mM) and methyl jasmonate (MJ) (01.00 mM). Bioprocess kinetics optimized by response surface methodology and monitored by high-performance liquid chromatography revealed a clear dependence of growth and squalene content (SQC) and yield (SQY) on the above regulators. Maximum SQC (10.02 ( 0.53 mg/g dry biomass) and SQY (20.70 ( 1.00 mg/L) were achieved using 0.442 mM terbinafine plus 0.044 mM MJ after 28 h and 0.300 mM terbinafine after 30 h, respectively. A 10-fold increase in SQY was achieved in comparison to that in the absence of regulator. The ruggedness of optimum conditions for SQY was verified for five industrial strains. The cellular lipid fraction (∼12% of dry biomass) was rich in squalene (1213%). Results are encouraging toward bioprocess scale up. KEYWORDS: squalene, wild-type Saccharomyces cerevisiae strains, terbinafine, methyl jasmonate, squalene epoxidase
’ INTRODUCTION The incorporation of functional lipids into food products has expanded in the last few decades because each of these lipid classes presents specific health effects.1 For example, the use of phytosterols, phytostanols, and their esters has become a widely accepted, successful innovation among functional foods.2 Squalene, a precursor in the biosynthesis of sterols and steroids, is a functional lipid associated with various beneficial properties, despite some uncertainty. Squalene intake becomes effective through the everyday diet or after intravenous injection.3 This terpenoid hydrocarbon (C30H50, 6,10,15,19,23-hexamethyl2,6,10,14,18,22-tetracosahexaene) has been associated with a chemopreventive effect on colon cancer upon consumption of virgin olive oil, a decrease in chemotherapy-induced side effects, scavenging properties for toxic metabolites, protection against bacterial and fungal infections, and effective inhibition of photoperoxidation.3,4 Among known foods, virgin olive oil prevails in dietary squalene content (regularly 7 mg/g),5 whereas other fruit or seed oils contain much lower quantities (e.g., pumpkin seed oil,
