Culture of Euglena gracilis growing mixotrophycally is subject to fungal infection. 4 fungicides which widely used in agriculture to protect plants against fungal infections were tested for suppression of the development of spores or mycelia of pathogenic fungi in the E. gracilis culture. It was analyzed the effect of propineb, mancozeb, benomyl and the mixture (1:1) of famoxadon and cymoksanil added to the liquid and agar mineral nutrient medium containing glutamic acid as an exogenous carbon source. It is shown that the contact fungicides propineb and mancozeb in tested concentrations kill algal cells but do not suppress the growth of fungi. Benomyl, as well as a combined preparation of famoxadon and cymoksanil (1:1), inhibits the growth of fungi and did not suppress the cell growth of microalgae E. gracilis. The experiments, directed to detection of the viability of spores in the culture suspensions, showed that only benomyl at concentrations which do not affect the growth of microalgae, significantly reduces the number of viable spores. Thus, as a result of the study, it was found that benomyl at a concentration of 20 µg/ml is of potential value in eliminating fungal contaminants from culture of E. gracilis.

Keywords: Euglena gracilis, fungicides, benomyl, microfungal contamination

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