Optimization of various parameters for selenium enriched yeast production

Selenium is an essential trace element for humans, animals and poultry. It belongs to body’s antioxidant defense system. There are two major sources of selenium i.e. organic and inorganic. Selenium enriched yeast is the finest source of organic selenium. Yeast production can easily be achieved in laboratory as it utilizes soluble sugars and organic acids to yield biomass with high protein content. In this study the experiments were designed for optimizing culture conditions for the production of selenium enriched yeast. The statistical analysis of the data was performed on statistical software JMP predicted variables for optimization. The data of variables covered a wide range of values for fermentation temperature, shaking speed, pH, incubation time, Selenium concentration and selenium adding time to built-in response for variables to specific yeast biomass. Morphological characteristics such as colonial morphology (colony shape, colour, and surface appearance) and yeast biochemical identification on metabolized glucose sucrose, lactose, cellibiose express genes that activate the synthesis of yeast. The optimized values for Temp 25oC, pH 4, Se conc. 30 µg/ml, addition of Se after 9 hr of incubation, shaking speed 130rpm and incubation time 48 hrs yielded total biomass (65.59g/L) and selenium accumulation (46.23mg/kg) respectively. It was concluded that using a culture medium supplemented with 30 μg/mL sodium selenite identified the optimum fermentation conditions initial sodium selenite (Na2SeO3) concentration, initial pH and temperature) from Saccharomyces cerevisiae for maximal total Se yield of selenium-enriched yeast.