Toxic Effect of Bisphenol A Causes Oxidative Stress in cyanobacterium Gloeocapsopsis crepidinum

Microalgae are good tools for toxicity indicators in aquatic habitats. The present study was carried out to evaluate the toxicity of bisphenol A at different concentrations (1, 5, 10, 20, 50, 75, 100) mg/l and the oxidative response induced by this exposure using the cyanobacterium Gloeocapsopsis crepidinum. The results showed a decrease in the algal biomass rate with increasing concentrations of bisphenol A, while the Half inhibition concentration (IC50) of BPA was 2.68 mg/l. The chlorophyll-a and carotenoids recorded highest value in the control group, which were 0.96 and 0.56 µg/ml, while the concentrations of these pigments decreased with increasing concentrations of BPA, their lowest value being recorded at (0.54 and 0.35) µg/ml at a concentration of 100 mg/l.  The results showed that Catalase (CAT) and Ascorbate peroxidase (APX) enzymes recorded a higher value of (0.34 and 4.66) U/g at 100 mg/l BPA, while the lowest values of these enzymes recorded 0.10 and 3.7 U/g in the control group respectively. While the Superoxide dismutase (SOD) enzyme recorded a high value of 22.22 U/g at 1 mg/l BPA and decreased with a lower value of 19.46 U/g at 100 mg/l. In addition, Glutathione (GST) showed lower values of 5.413 µmole/g in the control group and increased at higher values at a concentration of 100 mg/l which reached to 18.68 µmole/g. Nevertheless, the indication of cell damage such as Malondialdehyde (MDA) and Reactive Oxygen Species (ROS) recorded lowest values of 0.13 and 14.153 µmole/g in the control group, while higher values recorded with increasing concentrations of BPA were recorded at 3.487 and 74.4 µmole/g at 100mg/l BPA, respectively. All treatments were statistically analyzed with p ≤ 0.05 as significant differences were found between all treatments.  This study concluded that cyanobacteria G. crepidinum have the ability to resist the toxic effects of bisphenol A by increasing antioxidant production in their bodies, so they can be considered biological tools to eliminate toxic compounds in aquatic environments.