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CNAA / Theses / 2009 / June /

Biotehnology of yeasts cultivation and obtaining of sterols preparations

Author: Molodoi Elena
Degree:doctor of biology
Speciality: 03.00.23 - Biotechnology
Scientific adviser: Agafia Usatîi
doctor habilitat, professor, Institute of Microbiology and Biotechnology of the ASM
Scientific consultant: Anatol Rotaru (decedat)
doctor habilitat, professor, Academy of Economic Studies of Moldova
Scientific council:


The thesis was presented on the 19 June, 2009
Approved by NCAA on the 1 October, 2009


Adobe PDF document0.76 Mb / in romanian


oleobiotehnology, Saccharomyces carlsbergensis, Saccharomyces cerevisiae, Rhodotorula gracilis, lipids, sterols, ergosterol, carotenoids, nutrition medium, millimeter waves


This work presents the synthesis of obtained results of investigation of features of directed cultivation of strain of yeasts with high productivity of sterols, with the aim of elaboration of tehnology of obtaining of biomass with high biochemical value contents and of sterols preparations on the base of this biomass.

As the result of screening the strain of yeasts Saccharomyces carlsbergensis-B with high capacity of sterols biosynthesis (3,9% in dry biomass) was selected, morpho-cultural and physiologo-biochemical properties of selected strain have been established.

Preferred sources of nutrition for the directed cultivation of yeasts, precursors and inductors of sterols biosynthesis of strain Saccharomyces carlsbergensis CNMN-Y-15 have been established.

Two mediums of culture through which it is possible to increase the productivity and the sterols content in the biomass of yeast Saccharomyces carlsbergensis CNMN-Y-15 have been elaborated due to the application of mathematical planning method of experiments. Nutrition medium optimized MN-3, which includes the utilization of coordinative compounds of zinc in combination with melasa, allow the obtaining of 8,36 g*L-1 of dried biomass. Another nutrition medium optimized MN-S supplemented with glucoze and acetate of manganese contribuie to the obtaining of high content of sterols (13,20% of dried biomass).

Millimeter waves of low intensity contribuie to the important modifications on the level of population and biosynthetic activity of yeasts. Biological effect of millimeter waves action depends on the strains yeasts, parameters of irradiation, and phase of formation of population.

The procedure of extraction of ergosterol from the biomass of yeasts Saccharomyces which increases the final content and decreases the time of extraction have been elaborated.

The technological scheme of obtaining of 4 valuable bioproducts from the biomass of Saccharomyces carlsbergensis CNMN-Y-15 have been elaborated as the result of combination of precursors and inductors of sterols biosynthesis, optimal parametres of application of millimeter waves of low intensity and the new procedure extraction of sterols.