The Effect of Bisphenol A on Growth, Morphology, Lipid Peroxidation, Antioxidant Enzyme Activity, and PS II in <italic>Cylindrospermopsis raciborskii</italic> and <italic>Scenedesmus quadricauda</italic>.

To investigate the effect of bisphenol A (BPA) on <italic>Cylindrospermopsis raciborskii</italic> (Cyanobacteria) and <italic>Scenedesmus quadricauda</italic> (Chlorophyta), we grew the two species at BPA concentrations of 0, 0.1, 1, 2, 5, 10, and 20 mg/L and examined their growth, lipid peroxidation, antioxidant enzyme activity, and chlorophyll a fluorescence. The 96-h EC₅₀ values (effective concentration causing 50% growth inhibition) for BPA in <italic>C. raciborskii</italic> and <italic>S. quadricauda</italic> were 9.663 ± 0.047, and 13.233 ± 0.069 mg/L, respectively. A significant reduction in chlorophyll a concentration was found in <italic>C. raciborskii</italic> and <italic>S. quadricauda</italic> when BPA concentrations were greater than 1 and 2 mg/L, respectively. Furthermore, <italic>F</italic>_v/<italic>F</italic>_m, Δ<italic>F</italic>/<italic>F</italic>_m′, and qP decreased significantly at 10 mg/L BPA in <italic>C. raciborskii</italic> but started to decrease at 10 mg/L in <italic>S. quadricauda.</italic> The changes in chlorophyll fluorescence parameters (<italic>α</italic>, rETR_max) that were obtained from the rapid light response curves of both algae species showed similar responses to <italic>F</italic>_v/<italic>F</italic>_m, Δ<italic>F</italic>/<italic>F</italic>_m′, and qP under BPA-induced stress. Values for all of the chlorophyll fluorescence parameters in <italic>S. quadricauda</italic> were higher than in <italic>C. raciborskii</italic>; however, the nonphotochemical quenching measured in <italic>C. raciborskii</italic> was considerably higher than it was in <italic>S. quadricauda</italic>. In addition, lipid peroxidation (determined as MDA content) and antioxidant enzyme activities (SOD and CAT) increased in both species as the BPA concentration increased. These results suggest that <italic>C. raciborskii</italic> is more sensitive to the effects of BPA than <italic>S. quadricauda</italic> and that photosystem II might be a target for the activity of BPA in vivo. [ABSTRACT FROM AUTHOR]