INTRODUCTION
Microbiological synthesis products (enzymes) find wide application in various branches of petrochemical, food, and processing industries, medicine, pharmacology, etc. The principal stages of fermentation are the selection of a producing strain and the determination of conditions for its cultivation, during which the microbiosynthesis of a certain enzyme proceeds. Fermentation is most often implemented as a continuous process (maintaining the cultivation conditions throughout the entire period of its duration), but many metabolites can be obtained only via batch synthesis with the withdrawal of a product at the end of the process. The regularities governing the formation of an enzyme complex strongly depend on many process parameters (physicochemical, engineering, biological, and other factors [1–7]), the adjustment of which provides the efficient organization of this process. The technology of such a process usually ensures the simultaneous attainment of a maximum of both productivity and quality at minimum expenditures.
Since the synthesized enzyme is extracted from a cultivated biomass or a cultural liquid, it is necessary to perform a series of studies on the effect of the birth and death rates of cultivated population members on the amount of formed biomass. The consumption of time in this project will be reduced by constructing a mathematical model, which adequately describes the process of fermentation.
The objective of this work is to construct mathematical models providing the system description of the microbial cultivation and biosynthesis of the target enzyme and to study the kinetic regularities governing the duration of batch cultivation.
OBJECTS AND METHODS OF STUDY
Biokinetic regularities were studied using the cultivation of the Escherichia coli strain, a recombinant Rhoodesporidium foruloides L-phenylalanine ammonia-lyase producer, grown at the Research Institute of Bioengineering of the Kemerovo Institute of Food Science and Technology [8–10]. The submerged batch cultivation of yeast in a fermenter was performed following the existing producer recommendations (in a culture medium containing (g/l): glucose, 20.0; peptone, 10.0; yeast extract, 5.0), at a temperature of 26°C for 24 h in the regime of non-controlled pH. Control measurements were performed every half hour beginning from the moment of pitching. The biomass and protein concentrations were determined from the absorbance in compliance with the manufacturer’s manuals for an UV-1800 spectrophotometer (Shimadzu, Japan) [9].
