The role of microplastics in microalgae cells aggregation: A study at the molecular scale using atomic force...

Area of Science:

• Environmental Science
• Microbiology
• Biophysics

Background:

• Plastic pollution is a major threat to aquatic ecosystems.
• Microalgae are a crucial entry point for pollutants into the food chain.
• Understanding plastic-microalgae interactions is vital for assessing ecological impacts.

Purpose of the Study:

• To investigate how plastic microparticles affect the aggregation of freshwater microalgae (Chlorella vulgaris).
• To elucidate the mechanisms behind plastic particle-cell interactions.
• To model the consequences of plastic pollution on microalgae.

Main Methods:

• Biophysical characterization of plastic microparticles using atomic force microscopy.
• Optical imaging and separation experiments to observe microalgae aggregation.
• Single-cell force spectroscopy to analyze cell-particle interactions.

Main Results:

• Plastic microparticles possess rough, irregular, and hydrophobic surfaces, similar to environmental particles.
• Microalgae exposed to plastic particles produced exopolysaccharides (EPS), leading to cell aggregation.
• Direct hydrophobic interactions between microalgae cells and plastic particles were observed.
• Aggregation occurred both during co-culture and upon subsequent exposure of microalgae to plastic particles.

Conclusions:

• Plastic microparticles trigger microalgae aggregation via two primary mechanisms: inducing EPS production or direct hydrophobic interactions.
• These findings are critical for understanding the large-scale ecological consequences of plastic pollution in aquatic food webs.