Bioaccumulation and impact of levonorgestrel on the growth, photosynthetic pigments, and oxidative stress response of Chlorogonium elongatum
摘要
Levonorgestrel (LNG) is the active ingredient of most oral contraceptives and has been identified in water bodies. The presence and impact of this drug in aquatic ecosystems is of interest because non-target aquatic organisms, such as microalgae, could be adversely affected, but the extent of this impact is currently unknown. This study explored the bioaccumulation and impacts of LNG on cell growth, photosynthetic pigment production, and oxidative stress responses of the green alga Chlorogonium elongatum. LNG caused a reduction in growth (cell density) and an elevation in the total chlorophyll content of C. elongatum with increasing concentrations compared with control. Total chlorophyll content was highest at 1000 ng L−1 and lowest at 10 ng L−1 of day 7 exposure to LNG compared to the control. In comparison to the control and lower LNG treatments, the level of intracellular hydrogen peroxide increased significantly (p < 0.05) at 10,000 ng L−1. The concentration of malondialdehyde and peroxidase and glutathione-S-transferase activities were elevated following treatment with LNG but not significantly (p > 0.05). The contraceptive bioaccumulated in C. elongatum, with the highest bioaccumulation factor of 3.21 at 10,000 ng L−1 LNG and the lowest of 0.00 at 1 ng L−1 LNG. The study revealed that LNG bioaccumulation in C. elongatum not only affects its growth and photosynthesis but also induces oxidative stress, suggesting potential risks to aquatic ecosystems and highlighting the capacity of microalgae for bioremediation of hormonal pollutants.