Transcriptome analysis of the effect of bisphenol A exposure on the growth, photosynthetic activity and risk of microcystin-LR release by Microcystis aeruginosa.

Bisphenol A (BPA), one of the most abundant endocrine-disrupting compounds, is frequently detected in diverse aquatic environments, which imposes a substantial burden on the aquatic ecosystem. However, the correlation between BPA levels and the outbreak of a cyanobacterial bloom remains largely unknown. In this study, the cellular and transcriptomic responses to BPA exposure were investigated. Exposure to a high concentration of BPA (50 μM) significantly inhibited the growth of cyanobacterial cells, with the highest inhibition ratio of 51.3%, photosynthesis, and the release of extracellular microcystin-LR (MC-LR) (p < 0.05). However, exposure to low concentrations of BPA (0.1 and 1 μM) also affected these indicators, but the differences were closely related to the growth phase of the cyanobacterial cells. In addition, an imbalance between the antioxidant system and oxidative stress was observed in cyanobacteria under BPA stress. Folate biosynthesis, ABC transporters and ubiquinone and other terpenoid-quinone biosynthesis were the central metabolic pathways triggered by BPA stress. The up-regulated genes, including queC, VTE3 and PsbO were the controller of cellular growth and photosynthesis. The down-regulated genes, including VET4, MlaE and DnaA were potential biomarkers of oxidative damage. The up- and down-regulated genes, including CA, Ppc and CyoE were the main regulators of energy generation. The findings will provide important insights into the role of endocrine disruptors in the frequent outbreak of cyanobacterial blooms.