The aim of the B. Sc Thesis was to investigate toxic effects of selected metals on the reproduction of algae Chlamydomonas reinhardtii using parameter such as cell density, inhibition of reproduction, effective concentration and fluorescence. The objectives of the thesis are to investigate and compare the effect of selenium(VI) and arsenic(V) metals at EC20 and to determine the inhibition of algal reproduction by WT using the difference in median fluorescence. In the first set of studies, C. reinhardtii cells were treated with different concentrations of arsenic(V) and selenium(VI) in separate experiments. The work was carried out in a suitably protected environment. A growth inhibition test was carried out for 72 hours based on the OECD 201 guidelines for algae or cyanobacteria. The algal culture from the library was first examined morphologically using a microscope and the best culture was transferred into a flask with TAP medium and placed on a shaker in a growth chamber to multiply the cells to the late exponential phase. Subsequently, treated samples and controls were transferred every 24 hours to a microtiter plate and using a flow cytometer recorded fluorescence and cell density data, which were used for data analysis in the second part of the thesis. According to our results, the selected metals may be harmful to algae in aquatic environments. Arsenic(V) is toxic to C. reinhardtii from 7 mg/L onwards and almost completely inhibits growth at 48 mg/L (95% inhibition). Selenium(VI) is toxic to selected algae from 0.2 mg/L onwards and causes 99% inhibition of reproduction at 2 mg/L. The experimentally obtained EC20 for arsenic(V) is 15.4 mg/L, while the E20 for selenium(VI) is 0.4 mg/L, indicating a higher toxicity of selenium. The treatment of the mutant mixture showed a lower sensitivity compared to wild type C. reinhardtii based on cell density and inhibition. The obtained data indicate toxicity of the selected elements represent an environmental concern.
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