Saccharomyces cerevisiae var. boulardii (S. boulardii) is a probiotic yeast strain that is the only yeast probiotic approved by the FDA (U.S. Food and Drug Administration) for clinical use. It is commonly used to prevent or treat acute diarrhea and other gastrointestinal disorders, including antibiotic-associated diarrhea caused by Clostridium difficile infections. The lack of a registered and available technology for the cultivation of probiotic yeast, as well as the release of the drug in a dry active form, poses several fundamental tasks for the study. In addition to the selection of a nutrient medium and the development of a technology for obtaining biomass, it is necessary to create conditions for increasing the xeroresistance of the crop. During the life cycle of Saccharomyces cerevisiae boulardii yeast probiotic lyophilisate, the culture is exposed to many stresses. The occurrence of stress contributes to a decrease in the activity of the strain, as well as when exposed to oxidative and thermal stresses, programmed cell death, which poses a risk to the viability of probiotic microbes. As a result, the metabolic activity of yeast decreases, and the number of non-viable cells increases. One of the ways to preserve the physiological activity of cells after dehydration is the directed synthesis of trehalose. Studies conducted with baker's yeast Saccharomyces cerevisiae indicate that trehalose is synthesized in the absence of the Crabtree effect in the stationary stage of growth at a temperature of 37 to 42 ℃. There is no information about the biosynthesis of trehalose in the yeast Saccharomyces cerevisiae boulardii. The study reflects the dependence of the carbon composition and cultivation parameters on the process of trehalose accumulation by the cell. Comparisons of the potential for trehalose formation in Saccharomyces cerevisiae boulardii cultures from Saccharomyces cerevisiae are presented. As a result of the research, it has been established that to obtain xeroresistant yeasts containing more than 15 % trehalose, the cultivation of Saccharomyces cerevisiae boulardii at a temperature of 39–40 ℃ with a deficiency of nutrients in the medium is facilitated.

1. U.S. Food and Drug Administration: official website. URL: https://www.fda.gov (in Russian)

2. Ranjha M.M.A.N., Shafique B., Batool M. et al. Nutritional and health potential of probiotics: a review. Applied Sciences. 2021. vol. 11. no. 23. p. 11204. doi:10.3390/app112311204

3. McFarland L.V., Li T. Efficacy and safety of Saccharomyces boulardii CNCM I-745 for the treatment of pediatric acute diarrhea in China: a systematic review and meta-analysis. Frontiers in Cellular and Infection Microbiology. 2025. vol. 15. p. 1587792. doi:10.3389/fcimb.2025.1587792

4. Liao W., Chen C., Wen T. et al. Probiotics for the prevention of antibiotic-associated diarrhea in adults: a meta-analysis of randomized placebo-controlled trials. Journal of Clinical Gastroenterology. 2021. vol. 55. no. 6. pp. 469-480. doi:10.1097/MCG.0000000000001464

5. Mourey F., Sureja V., Kheni D. et al. A multicenter, randomized, double-blind, placebo-controlled trial of Saccharomyces boulardii in infants and children with acute diarrhea. The Pediatric Infectious Disease Journal. 2020. vol. 39. no. 11. pp. e347-e351. doi:10.1097/INF.0000000000002849

6. Bader M.S., Hawboldt J., Main C. et al. Review of high dose vancomycin in the treatment of Clostridioides difficile infection. Infectious Diseases. 2020. vol. 52. no. 12. pp. 847-857. doi:10.1080/23744235.2020.1800080

7. Tariq R., Tahir M.W., Hayat M. et al. Systematic review and meta-analysis: safety and efficacy of Saccharomyces boulardii for prevention of Clostridioides difficile infection. Journal of Gastrointestinal Infections. 2022. vol. 12. no. 2. pp. 94-100. doi:10.1055/s-0043-1760738

8. Sirsat G.M., Saraf R. Beneficial Effect of Probiotic Saccharomyces Boulardii in Management of Acute Diarrhoea of Children-A Randomized Controlled Trial. Research Journal of Medical Sciences. 2024. vol. 18. pp. 500-504. doi:10.36478/makrjms.2024.11.500.504

9. Ting T.Y., Lee W.J., Goh H.H. Molecular Genetics and Probiotic Mechanisms of Saccharomyces cerevisiae var. boulardii. Probiotics and Antimicrobial Proteins. 2025. pp. 1-15. doi:10.1007/s12602-025-10634-y

10. Duffey H.E., Watson A.K., McCann S.M. et al. Genomic and phenotypic comparison of Saccharomyces cerevisiae and Saccharomyces boulardii. bioRxiv. 2025. p. 2025.09.08.674931. doi:10.1101/2025.09.08.674931

11. Samakkarn W., Vandecruys P., Moreno M.R.F. et al. New biomarkers underlying acetic acid tolerance in the probiotic yeast Saccharomyces cerevisiae var. boulardii. Applied Microbiology and Biotechnology. 2024. vol. 108. no. 1. p. 153. doi:10.1007/s00253-023-12946-x

12. Gopalan S., Al-Sinawi B., Al-Moqbali Z. et al. Unique properties of yeast probiotic Saccharomyces boulardii CNCM I-745: A narrative review. Cureus. 2023. vol. 15. no. 10. p. e46314. doi:10.7759/cureus.46314

13. Hudson L.E., McDermott C.D., Stewart T.P. et al. Characterization of the probiotic yeast Saccharomyces boulardii in the healthy mucosal immune system. PLoS One. 2016. vol. 11. no. 4. p. e0153351. doi:10.1371/journal.pone.0153351

14. Rajkowska K., Kunicka-Styczynska A. Probiotic activity of Saccharomyces cerevisiae var. boulardii against human pathogens. Food Technology and Biotechnology. 2012. vol. 50. no. 2. pp. 230-236. doi:10.17113/ftb.50.02.12.2693

15. Rajkowska K., Kunicka-Styczynska A. Probiotic properties of yeasts isolated from chicken feces and kefirs. Polish Journal of Microbiology. 2010. vol. 59. no. 4. pp. 257-263. doi:10.33073/pjm-2010-039

16. Suvarna S., Dsouza J., Ragavan M.L. et al. Potential probiotic characterization and effect of encapsulation of probiotic yeast strains on survival in simulated gastrointestinal tract condition. Food Science and Biotechnology. 2018. vol. 27. no. 3. pp. 745-753. doi:10.1007/s10068-018-0310-8

17. Gut A.M., Vasiljevic T., Yeager T. et al. Salmonella infection-prevention and treatment by antibiotics and probiotic yeasts: a review. Microbiology. 2018. vol. 164. no. 11. pp. 1327-1344. doi:10.1099/mic.0.000709

18. Fakruddin M., Hossain M.N., Ahmed M.M. Antimicrobial and antioxidant activities of Saccharomyces cerevisiae IFST062013, a potential probiotic. BMC Complementary and Alternative Medicine. 2017. vol. 17. p. 64. doi:10.1186/s12906-017-1591-9

19. Banik A., Mondal J., Rakshit S. et al. Amelioration of cold-induced gastric injury by a yeast probiotic isolated from traditional fermented foods. Journal of Functional Foods. 2019. vol. 59. pp. 164-173. doi:10.1016/j.jff.2019.05.039

20. Hsu S.A., Chou J.Y. Yeasts in fermented food and kefir: in vitro characterization of probiotic traits. Journal of Animal & Plant Sciences. 2021. vol. 31. no. 2. pp. 461-470. doi:10.36899/JAPS.2021.2.0245

21. Sanders M.E., Merenstein D., Merrifield C.A. et al. Probiotics for human use. Nutrition Bulletin. 2018. vol. 43. no. 3. pp. 212-225. doi:10.1111/nbu.12334

22. World Health Organization. Evaluation of certain contaminants in food: ninety-third report of the Joint FAO/WHO Expert Committee on Food Additives. WHO, 2023. 125 p.

23. Aghamohammad S., Hafezi A., Rohani M. Probiotics as functional foods: How probiotics can alleviate the symptoms of neurological disabilities. Biomedicine & Pharmacotherapy. 2023. vol. 163. p. 114816. doi:10.1016/j.biopha.2023.114816

24. Martín R., Olivares M., Marín M.L. et al. Probiotic potential of 3 lactobacilli strains isolated from breast milk. Journal of Human Lactation. 2005. vol. 21. no. 1. pp. 8-17. doi:10.1177/0890334404272393

25. Trevelyan W.E., Harrison J.S. Studies on yeast metabolism. I. Fractionation and microdetermination of cell carbohydrates. Biochemical Journal. 1952. vol. 50. no. 3. pp. 298-303. doi:10.1042/bj0500298

26. Ferreira J.C., Neves M.J., Destruhaut A. et al. Comparison of three different methods for trehalose determination in yeast extracts. Food Chemistry. 1997. vol. 60. no. 2. pp. 251-254. doi:10.1016/S0308-8146(96)00337-5

27. Meledina T.V., Ivanova V.A., Fedorov A.V. Apparatus and methodological base of experiments in the field of food biotechnology of products from plant raw materials. Moscow: Publishing House VGUIT, 2022. 156 p. (in Russian)

28. Chechina O.N., Martynov K.A., Sokol O.V. et al. Patent RU 2528872. Method for cultivating baker's yeast. 2014. (in Russian)