Physiological impact of perfluorooctanoic acid (PFOA) on the cyanobacterium Microcystis aeruginosa

Perfluorooctanoic acid (PFOA) is a surfactant that is detected in small quantities across various environments away from its manufacturing zones. Despite the widespread detection of PFOA in aquatic ecosystems, the impact of this compound on phytoplankton populations remains poorly understood. This study aimed to determine the physiological effects of PFOA on Microcystis aeruginosa. The cyanobacterium was exposed to 1‒10 000 μg l‒1 PFOA for 7 days under controlled laboratory conditions. The EC50 of PFOA for the test species after 7 days of exposure was 30.03 μg l‒1. Cell density significantly decreased at all PFOA concentrations (1‒10 000 μg l‒1). Chlorophyll a and carotenoid concentrations increased on day 1 (except for 1 μg l‒1, the lowest PFOA treatment) but then decreased across all treatment concentrations on day 7 of the experiment. When M. aeruginosa was exposed to PFOA, the total lipid, protein and carbohydrate content generally increased across all treatment concentrations. The concentration of intracellular hydrogen peroxide increased with increasing surfactant concentrations. In different treatments, lipid peroxidation increased, with 100 μg l‒1 PFOA producing the highest malondialdehyde content. Peroxidase and glutathione S-transferase activities increased across all treatment concentrations, demonstrating progressive changes consistent with the increase in reactive oxygen species observed. Total microcystin concentration increased in cultures exposed to 1000 and 10 000 µg l‒1 PFOA. These findings suggest that PFOA can adversely affect the survival of M. aeruginosa populations in contaminated aquatic ecosystems, with potential cascading effects on the general health of the environment.