Effect of silver nanoparticles on growth, chlorophyll content and phenolic compounds of Nannochloropsis oculata

Silver nanoparticles (Ag NPs) have been widely used in various industries, thus inevitably released into the aquatic ecosystem. Microalgae have important role in aquatic ecosystem, so in this study, the effect of different concentrations of Ag NPs (0, 1, 5, 10, 25 and 50 mg/L) investigated on Nannochloropsis oculata. The results showed that the growth rate and the content of chlorophyll a significantly decreased in algal cells treated with Ag NPs compared to control. Also, the content of carotenoids significantly increased, while the phenolic compounds significantly decreased in response to Ag NPs. Increase of carotenoids probably is a defensive response in this microalga under stress condition. The TEM images of algae cells treated with Ag NPs showed that NPs damaged the algal cell wall.