Enhanced production of squalene in the thraustochytrid Aurantiochytrium mangrovei by medium optimization and treatment with terbinafine

Squalene is an effective chemopreventive agent in reducing the incident of coronary heart disease and cancer. It is also a strong antioxidant used extensively in the food and cosmetic industries. Microbial sources of squalene are being explored in recent years. The objective of this study is to increase the squalene content and yield in the thraustochytrid, Aurantiochytrium mangrovei FB3 through medium optimization and the treatment with terbinafine, an inhibitor of squalene monooxygenase in the sterol biosynthetic pathway. The highest biomass concentration of 21.2 g l(-1) was obtained at a glucose concentration of 60 g l(-1), while the highest specific growth rate of 0.077 h(-1) and the growth yield coefficient of 0.44 g g(-1) based on glucose were achieved at a lower glucose concentration (30 g l(-1)). The addition of terbinafine led to a slight inhibition of cell growth whereas an obvious increase in squalene content was observed at terbinafine concentrations of 10 and 100 mg l(-1), which corresponded to an increase of 36 and 40% in squalene content, respectively compared to the control. The addition of terbinafine was thus effective in inducing the accumulation of squalene in A. mangrovei. This study not only demonstrated the production potential of squalene by A. mangrovei, but also provided novel information on the accumulation effect of terbinafine on the biosynthesis of an essential intermediate involved in sterol metabolic pathway.