Polystyrene nanoparticles regulate microbial stress response and cold adaptation in mainstream anammox process at low...

Area of Science:

• Environmental Science
• Microbiology
• Environmental Engineering

Background:

• Nanoplastic pollution is a significant environmental challenge, particularly in aquatic ecosystems.
• The bioaccumulation of nanoplastics complicates wastewater treatment processes.
• Anaerobic ammonia oxidation (anammox) is a key process for nitrogen removal in wastewater treatment.

Purpose of the Study:

• To investigate the impact of polystyrene nanoparticles (PS-NPs) on the microbial dynamics of the anammox process.
• To understand the fate and regulation mechanisms of PS-NPs in wastewater treatment.
• To assess the effects of varying PS-NP concentrations on nitrogen removal efficiency and anammox bacteria.

Main Methods:

• Utilized mainstream anaerobic ammonia oxidation (anammox) reactors with varying concentrations of PS-NPs.
• Monitored nitrogen removal efficiency (NRE) and microbial community structure.
• Assessed oxidative stress markers (ROS, LDH) and cell membrane integrity.
• Investigated molecular mechanisms including heme c content, molecular docking, and western blotting for cold shock proteins (CSPs).

Main Results:

• PS-NPs at 0.1-0.5 mg L^-1 had no significant effect on NRE.
• NRE decreased from 94.9% to 77.0% with increasing PS-NP concentration (0.5-2 mg L^-1).
• PS-NPs induced oxidative stress, cell damage, reduced heme c, and inhibited anammox activity.
• Cold shock proteins (CSPs) were found to bind PS-NPs, reducing anammox performance at low temperatures.

Conclusions:

• Polystyrene nanoparticles negatively impact anammox process performance and microbial community structure.
• Oxidative stress and cell damage are key mechanisms of PS-NP toxicity.
• Cold shock proteins play a role in the reduced efficiency of anammox processes exposed to PS-NPs, especially at lower temperatures.