Ecological Systems and Devices Annotation << Back Fungicidal and Antioxidant Activity of Cyano-Bacterial Communities Isolated from the Natural Environment Bataeva Yu.V., Pokhilenko V.D. Nitrogen-fi xing cyanobacteria are successfully used in many countries, which contributes to increasing soil fertility, increasing yields due to nitrogen fi xation, stimulating growth and protecting agricultural crops from diseases. In this paper, the phytotoxic, fungicidal, antioxidant activity of soil cyano-bacterial communities isolated in the Astrakhan region is characterized. All the studied communities did not show a toxic effect on the watercress plant. An active antagonistic effect of cyano-bacterial communities was found № 2, № 11, № 15, № 21 on phytopathogenic fungi of the genera Fusarium, Phythium, Alternaria. The antioxidant activity of the studied communities has been established. The culture liquid of community No. 21 had a pronounced antioxidant activity of 36.1 % and the water-alcohol extract of community № 2 in the volume of 100 μl 39.6 %. Keywords: cyano-bacterial communities, cyanobacteria, fungicidal activity, antioxidant activity. DOI: 10.25791/esip.11.2023.1409 Pp. 10-23.