Modern microbiological approaches to obtaining a strain of baker’s yeast promising for the creation of enriched food ingredients

The aim of the study is to use modern microbiological approaches to obtain a new strain of baker's yeast. The objects of the study were strains of baker's yeast from the Laboratory of Baker's Yeast Biotechnology of the Institute of Food Biotechnology. Selection and screening of the yeast strain were carried out by clonal plating of the original strain cells on agar media with glucose-asparagine medium (8 % DM) and with malt wort (12 and 18 % DM). The content of crude protein in the yeast biomass was determined by the Kjeldahl method on an automatic BEGER unit (Slovenia). Biomass accumulation was determined by the gravimetric method after cultivation, separating the solid and liquid fractions by centrifugation. Maltase, zymase and proteolytic activities were determined according to known methods. Ergosterol content - spectrophotometric method based on extraction with ethanol and sulfuric acid with triterpene compounds, at a wavelength of λ = 328 nm. The biomass (solid fraction) was separated from the filtrate by centrifugation in a laboratory centrifuge OPM-16 for 15 min at a rotor speed of 6000 rpm. Comparative studies were conducted to select the most productive strain of baker's yeast in terms of biochemical parameters. Comparative characteristics of yeast strains allowed us to select the most promising one - Saccharomyces cerevisiae Y-581, characterized by the ability to a higher level of protein synthesis, maltase, zymase activities, as well as ergosterol and osmosensitivity indicators. A two-stage selection and screening for the above indicators were carried out with the selected strain. As a result of microbiological approaches relative to the original strain S. cerevisiae Y-581, a population of Saccharomyces cerevisiae 581-GA-21c was isolated, characterized by a higher biosynthetic capacity not only in relation to ergosterol and protein, but also to the synthesis of enzymes, especially proteolytic ones. The isolated strain had a higher permeability of the cell membrane, as evidenced by its osmosensitivity indicators. The new strain also had distinctive features in morphological characteristics. This strain will be used in the field of obtaining enriched ingredients for the development of new types of food products.