Optimization and evaluation effect of ultrasound on the Saccharomyces cerevisiae (PTCC 5269) biomass in PDB medium based on whey using response surface methodology (RSM)

It is better to use agricultural by-products or waste for microbial production to reduce costs in the industry. Whey is one of the by-products that are rich in nutrients like vitamins, proteins and essential amino acids. Low-intensity ultrasound stimulation can improve membrane permeability and also help optimize the growth and reproduction of cells. According to high efficiency of Saccharomyces cerevisiae in the fermentation industry, the purpose of this study was to investigate the effect of ultrasound and the use of whey as alternative substrate carbohydrate substrates on the growth of Saccharomyces cerevisiae. PDB medium was formulated by adding a certain amount of dextrose and 1% whey. Ultrasound was applied to the medium containing yeast with three powers (2, 6 and 10 W) at different time periods (10, 20, 30 sec). The amount of cell mass was measured after fermentation process for control and treated samples. Optimum operating conditions obtained from RSM was the power of ultrasound 6 W, sonication time of 20 seconds and Add 10% glucose. Results showed that ultrasonic waves (with a power of 6 kW and 30 seconds) and medium containing whey increased the growth of yeast (from 8/14 to 6/64 mg). Based on the results, the low-power ultrasound can expedite fermentation process up to 4 times, also using nutritious compounds in whey new media could be created to increase fermentation output and prevent possible pollutions. Whey is used as a novel and applied method to enhance the growth of the Saccharomyces cerevisiae, which will ultimately increase the growth efficiency of the microorganisms.