Effects of various CO 2 concentrations on the productivity of cyanobacterial strains

. The accumulation of carbon dioxide (CO 2 ) in the atmosphere, as well as pollution of water objects with heavy metals, are environmental problems associated with numerous impacts on ecosystems. The cultivation of photosynthetic microorganisms that efficiently absorb CO 2 is a promising solution, since the biomass of cyanobacteria can be used to produce valuable bioproducts. Interest in the effect of high concentrations of CO 2 on the activity of cyanobacteria is growing in connection with studies of cleaning the atmosphere from industrial pollution using cyanobacteria as biofilters, due to their ability to grow rapidly in conditions of high CO 2 content in the atmosphere. Cyanobacteria are a convenient object for research due to the high growth rate and controllability of their biosynthesis. This article presents the results of the influence of different concentrations of carbon dioxide on the productivity of strains of cyanobacteria. Resistance to inhibitory concentrations of CO 2 is species-specific and varies over a wide range of values. The effect of carbon dioxide at a concentration of 2%, 4%, and 8% on the growth rate of cyanobacteria was studied, and a comparative assessment of the effect of increased carbon dioxide concentrations on biomass growth from the readings of optical density and fluorescence activity was carried out. It was determined that carbon dioxide concentrations of 2-4% have a positive effect on the productivity of the studied cultures of cyanobacteria. It was found that increasing the concentration of CO 2 to 8% leads to a decrease in growth rates of cyanobacteria. It was determined that the strain Cyanobacterium sp. IPPAS B-1200 was selected as the most productive strain from the studied cyanobacteria according to the yield of dry biomass, fluoresce activity and characterized by active growth at a concentration of CO 2 in air – 4%.