Sonochemical approach to obtain biomass of yeast Saccharomyces cerevisiae with high ergosterol content

Chemical synthesis of vitamin D2, an important nutrient for the human body, is difficult due to the asymmetric structure of the molecule of this vitamin. For this reason, the prospects for the development of biotechnological approaches for the synthesis of ergosterol as a precursor of this vitamin are enormous, which is the basis of this work. The use of yeast Saccharomyces cerevisiae was proposed as a producer. These microorganisms are the most well studied, widely used in the food industry, are safe, easy enough to cultivate. YPD medium containing yeast extract, peptone and dextrose was used as nutrient medium. The study investigated the possibility of using ultrasound as a factor of intensification of the process of ergosterol biosynthesis by yeast cell. Ultrasound, on the one hand, was considered as a factor intensifying the dissolved oxygen content in the nutrient medium, on the other hand, as a factor of stress effect on the yeast cells themselves. Cultivation and evaluation of the content of the desired metabolite were carried out in comparison with the control nutrient medium. The physiological state of yeast was evaluated by microscopy and the content of ergosterol in yeast biomass at the beginning and end of cultivation in two types of nutrient media (YPD and YPD-US). The results obtained showed the viability of the proposed approach for culturing Saccharomyces cerevisiae yeast using ultrasound treatment. It was found that ultrasound treatment leads to the accumulation of dissolved oxygen, the optimal modes of exposure were established - power 122 W and time 2 min. The increment of ergosterol content in yeast biomass cultured in nutrient medium after ultrasound treatment amounted to 13.2 mg %, which is 1.21 times more than in yeast biomass cultured in control nutrient medium. At the same time, the understanding of the mechanism of ultrasonic stimulation of ergosterol synthesis by yeast remains to be studied.