Abstract
The effects and the removal efficiency of bisphenol A (BPA) on two extremophilic Chlorophyta strains, an alkaliphilic Picocystis and a thermophilic Graesiella, were assessed. BPA was shown to inhibit the growth and photosynthesis of both species, but to a greater extent for Graesiella. The growth IC50 (4 days) was 32 mg L-1 for Graesiella and higher than 75 mg L-1 for Picocystis. Oxidative stress was induced in both strains when exposed to increasing BPA concentrations, as evidenced by increased malondialdehyde content. BPA exposure also resulted in an over-expression of antioxidant activities (ascorbate peroxidase, glutathione S-transferase and catalase) in Picocystis whereas they were repressed in Graesiella. Both species exhibited high BPA removal efficiency, reaching 72% for Picocystis and 52.6% for Graesiella at 25 mg L-1 . BPA removal was mostly attributed to biodegradation for both species. Overall, according to its extended tolerance and its removal capacity, Picocystis appeared to be a promising species for the BPA bioremediation even at high contamination levels.