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CNAA / Theses / 2018 / July /

Technology for obtaining of β-glucans from yeasts

Author: Chiselița Natalia
Degree:doctor of biology
Speciality: 03.00.23 - Biotechnology
Scientific adviser: Agafia Usatîi
doctor habilitat, professor, Institute of Microbiology and Biotechnology of the ASM
Institution: Institute of Microbiology and Biotechnology of the ASM


The thesis was presented on the 19 July, 2018
Approved by NCAA on the 23 November, 2018


Adobe PDF document0.57 Mb / in romanian


CZU 663.12:579.6 (043.2)

Adobe PDF document 5.54 Mb / in romanian
158 pages


Cultivation technology, yeasts, Saccharomyces cerevisiae, β-glucans, carbohydrates, proteins, nanoparticles, extra-high frequency millimeter waves


The thesis consistsof an introduction, four chapters, conclusions and recommendations, bibliography list with 281 references, 124 pages of the main content, 68 figures, 11 tables and 4 anexes. The obtained results were published in 36 scientific papers.

Field of study: 167.01- biotechnology, bionanotechnology.

Research goal: to develop an efficient innovative technology for β-glucan obtaining from yeasts.

Objectives: Selection of preferred nutrients and optimum conditions for submerged cultivation of S. cerevisiae CNMN-Y-20 strain to improve the biosynthesis of β-glucans; Elucidation of the action of the metal oxides nanoparticles on the biosynthesis of β-glucans and other cellular constituents of S. cerevisiae CNMN-Y-20 yeast; Evaluation of the extra-high frequency millimeter wave effects on the biosynthesis of β-glucans and other cellular constituents of S. cerevisiae CNMN-Y-20 yeast; Elaboration of technology of obtaining β-glucans from the yeasts biomass.

Scientific novelty of reasearch. For the first time, an innovative technology is proposed for S. cerevisiae yeast cultivation and β-glucan production, based on advantageous directed synthesis procedures, which contribute to improving the quality and reducing the cost of the final product. Preferential nutrients and two culture media for S. cerevisiae strain CNMN-Y-20 were selected, and specific culture conditions for enhancing β-glucan biosynthesis were established. For the first time, it has been demonstrated that TiO2 and ZnO nanoparticles used in yeast cultivation influence the biosynthesis process of β-glucans and other cellular constituents, the effect being dependent upon nanoparticle size and concentration. For the first time, the character of extra-high frequency millimeter wave action on the biosynthesis of β-glucans and other cellular components, depending on the frequency spectrum and the duration of irradiation, has been elucidated. For the first time, 2 new procedures for increasing β-glucan content in S. cerevisiae CNMN-Y-20 strain were elaborated, one of which was patented.

Important scientific problem, solved in the scientific work. The optimal biotechnological parameters of S. cerevisiae CNMN-Y-20 yeast cultivation were determined, which has contributed to the efficiency of the targeted synthesis of β-glucans, which enabled the elaboration of the technology for their obtaining.

Theoretical value. It is scientifically justified and demonstrated the possibility to direct the biosynthetic processes and to increase the β-glucan production potential diring S. cerevisiae CNMN-Y-20 yeast cultivation by the use of preferential nutrients, special cultivation conditions, nanoparticles and extra-high frequency milimeter waves as stimulators.

Practical value. There are proposed for valorisation: S. cerevisiae CNMN-Y-20 yeast strain, patented as a source of β-glucans; two variants of nutrient media and two directed synthesis processes with application of metal oxides nanoparticles and extra-high frequency milimeter waves as regulating factors, which ensure a significant increase of the β-glucans amount in the yeast biomass; the method of β-glucan extraction, the innovative character of which allows to reduce additional steps of cell wall destruction and β-glucans extraction; the bioproduct „Glucan-20” with high physiological activity.

Implementation of scientific results. The S. cerevisiae CNMN-Y-20 strain was deposited in the CNMN of IMB and used in scientific research. The polysaccharide bioproduct "Glucan20" has been used in diets of fish larvae and juveniles. (Implementation Acts: Nr. 1 from 17.07.2014, Nr. 3 from 17.07.2015, Nr. 4 from 10.10.2016, Nr. 85a from 04.09.2017).