Impact of ultrasound and medium condition on production of selenium-enriched yeast

Abstract

Background: Ultrasonication was used to stimulate the growth and selenium (Se) biotransformation in Saccharomyces cerevisiae. An optimization study for maximal Se accumulation in S. cerevisiae was conducted using the Plackett–Burman screening method and response surface methodology (RSM) for optimization of conditions. The variables influencing Se biotransformation by yeast, including duration and power of ultrasound, inoculum treatment with ultrasound, duty cycle, growth phase, time, shaking rate, inorganic salt concentration (Se, Zn, Mg, and K), and nitrogen and carbon sources as well as their concentrations were screened using the Plackett–Burman design.

Results: The main variables were carbon and Se concentration as well as ultrasound power and duty cycle. The lack of fit was insignificant (P > 0.01). The optimum condition for Se accumulation was obtained at Se concentration of 60 µg/ml, carbon source brix of 15, ultrasound of 90 W/L, and duty cycle of 40%.

Conclusions: The results showed that optimization of parameters and application of ultrasonication lead to a successful enhancement (2.78-fold) in the accumulation of selenium by S. cerevisiae. Such enriched yeast can be utilized in bread for increasing consumption of Se in the diet of patients with Se deficiency.