EFFECT OF CAFFEINE ON SELECTED REPRESENTATIVES OF PHOTOTROPHIC MICROORGANISMS

Aquatic ecosystems are becoming increasingly affected by micropollutants. The survival of microbial communities and entire aquatic ecosystems depends directly on their ability to adapt to this type of pollution. One of the most common micropollutants found in water bodies, especially in the vicinity of large cities, is caffeine. This stimulant directly affects living organisms and can cause changes in the species composition of microbial communities. However, the best way to decontaminate caffeine from the environment may be through the use of microorganisms. Therefore, in this study, the effect of caffeine on selected species of cyanobacteria and algae was investigated. The following strains of cyanobacteria: Geitlerinema cf. acuminatum (CCALA 141), Chlorogloeopsis fritschii (CCALA 039), Chlorogloeopsis fritschii (CCALA 1005), and Synechococcus granulates (CCALA 187) and a eukaryotic photosynthetic flagellate Euglena gracilis (strain Z) were selected. Probit analysis determined the minimum inhibitory concentration (MIC) of caffeine for each studied species. Also, the inhibitory effect of caffeine on each tested strain was monitored in vivo. Next, the strains were microscopically observed, and the potential change in their morphology under the caffeine treatment was recorded. The reproduction rate of all species in the study were moderately inhibited by caffeine, but during the cultivation, they were able to grow in comparison with the control sets. The most sensitive species was Geitlerinema cf. acuminatum (CCALA 141). The study also showed a significant effect of caffeine on morphology changes in the strains under investigation. Caffeine at low concentrations also showed a stimulating effect on the growth of the studied species. This may lead to their improved competence potential within microbial communities in the aquatic biotopes.