Abstract. The paper considers one of the types of continuous cultivation of microalgae with a set initial density of culture and a fixed time between dilutions. This mode has been given the term "ratetstat". It allows for the production of microalgae cultures that are unlimited in terms of biogenic elements, light, pH, and temperature, resulting in the stabilization of the biochemical composition of the biomass. After the culture adapting to the given external conditions, a constant productivity is obtained, and the dynamics of protein content in the biomass is studied at different stationary densities of the culture. By changing the stationary density, a culture with different light supply per unit of biomass is obtained. The aim of the work is to develop a mathematical model that allows us to explain the dynamics of protein accumulation in the biomass using the example of the green microalgae Teraselmis viridis in the ratetstat mode. When describing the biotransformation of biochemical substances, protein is chosen as the most significant component of the biomass of a physiologically active culture. In addition, protein is an integral component of the cell structure, which allows us to mathematically express the cell structures through its content. Experimental data on the protein content in the biomass and the productivity of T. viridis in a continuous cultivation mode for different stationary states of the culture are presented. The mathematical model is based on the assumption that in the ratetstat mode, the specific rate of protein synthesis is directly proportional to the amount of absorbed light energy per unit of the key multi-enzyme complex, where energy exchange reactions occur. It is assumed that some of the cellular proteins are destroyed during oxidative reactions at a constant specific rate. Analytical equations are obtained that describe the daily dynamics of the total protein concentration depending on the T. viridis biomass.

 

Key words: specific growth rate, specific rate of protein synthesis, protein production, linear growth, reduced luminous flux, light absorption coefficient