Аңдатпа
The accumulation of carbon dioxide (CO2) in the atmosphere, as well as pollution ofwater objects with heavy metals, are environmental problems associated with numerous impacts onecosystems. The cultivation of photosynthetic microorganisms that efficiently absorb CO2 is a promisingsolution, since the biomass of cyanobacteria can be used to produce valuable bioproducts. Interest inthe effect of high concentrations of CO2 on the activity of cyanobacteria is growing in connection withstudies of cleaning the atmosphere from industrial pollution using cyanobacteria as biofilters, due totheir ability to grow rapidly in conditions of high CO2 content in the atmosphere. Cyanobacteria are aconvenient object for research due to the high growth rate and controllability of their biosynthesis. Thisarticle presents the results of the influence of different concentrations of carbon dioxide on the productivity of strains of cyanobacteria. Resistance to inhibitory concentrations of CO2 is species-specific andvaries 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 increasedcarbon dioxide concentrations on biomass growth from the readings of optical density and fluorescenceactivity 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 CO2 to 8% leads to a decrease in growth rates of cyanobacteria. It was determined that thestrain 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 growthat a concentration of CO2 in air – 4%.Key words: Carbon dioxide, cyanobacteria, biomass productivity, fluorescence activity