Interaction between polyethylene terephthalate (PET) microplastic and microalgae (Scenedesmus spp.): Effect on the growth, chlorophyll content, and hetero-aggregation

Microplastics have become a global environmental concern due to their ubiquitous presence and persistence in the environment and have been identified as a major pollutant in aquatic environments. This study aimed to evaluate the effect of various concentrations of polyethylene terephthalate (PET) microplastic (25–200 mg/L) on the growth, chlorophyll content, and toxicity of Scenedesmus sp. from aquatic and terrestrial habitats over a period of 24 days. Our results showed that microplastics with higher concentration (200 mg/L) have a significantly higher inhibitory effect. Also, higher concentration of extracellular hydrogen peroxide (H2O2) extracellular polymeric substance (EPS) were found on microalgae exposed to the microplastic. Further, Scanning Electron Microscope (SEM) images revealed that microalgae attached to microplastic surfaces and formed hetero-aggregation. Overall, our study provided valuable information for understanding the complex effects of microplastics on microalgae, particularly in comparing the differential effects on aquatic and terrestrial Scenedesmus sp.