The growth and multiplication of the industrially significant yeast Saccharomyces cerevisiae is primarily determined by the balance of the composition of the nutrient medium used. In order to prevent a decrease in the speed of the biotechnology process and to achieve the optimal yield of the desired biosynthesis product (biomass), it is necessary to introduce such nutrient deficiencies as vitamins and trace elements into the nutrient medium. At present, there is much information about the influence of different environmental factors on the growth and multiplication of microorganisms. However, the potential possibilities of microbial cultures have not been fully used. Researchers during the preparation of nutrient media until recent time mainly use the methods of establishing one-factor dependence that are based on the principle of alternating change of each nutrient media factor with the others being constant. In this work, the impact on the biomass yield of various process parameters in their interactions is investigated. A multifactor dependence is established using the methods of mathematical design of an experiment. These methods allow both to study the effects of a large number of factors and to construct a mathematical model of the process revealing the quantitative value of each individual factor and to take into account the interfactor interactions in the system .The cultivation of the yeast Saccharomyces cerevisiae was conducted in a simple periodic culture. The factors used were: the amount of inoculum, the content of nitrogen, phosphorus and biotin in the medium. Using experimental data and multifactor analysis, it was found that under these conditions, the content of biotin in the medium mostly affects the biomass synthesis. It was established that, in an optimally composed media, the economic coefficient was independent of the size of the seeding. Moreover, it was shown that the size of the fund of free amino acids is inversely related to the consumption of the seeding: with an increase in the initial density of the population, the number of amino acids in cells decreases.

yeasts, nitrogen, phosphorus, biotin

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