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Polystyrene nanoparticles induce biofilm formation in Pseudomonas aeruginosa
Summary
Researchers found that polystyrene nanoparticles caused the common bacterium Pseudomonas aeruginosa to form thicker biofilms and become more resistant to antibiotics. The nanoplastics damaged bacterial cell membranes and triggered a stress response, prompting the bacteria to produce more protective biofilm as a defense mechanism. This is concerning for human health because it suggests nanoplastic pollution could make disease-causing bacteria harder to treat with existing antibiotics.
In recent years, micro/nanoplastics have garnered widespread attention due to their ecological risks. In this study, we investigated the effects of polystyrene nanoparticles (PS-NPs) of different sizes on the growth and biofilm formation of Pseudomonas aeruginosa PAO1. The results demonstrated that exposure to certain concentrations of PS-NPs significantly promoted bacterial biofilm formation. Meanwhile, we comprehensively revealed its mechanism whereby PS-NPs induced oxidative stress and altered bacterial membrane permeability by contacting or penetrating bacterial membranes. To counteract the stimulation by PS-NPs and reduce their toxicity, bacteria enhanced biofilm formation by upregulating the expression of biofilm-related genes, increasing EPS and virulence factors secretion, and enhancing bacterial motility through the participation of the quorum sensing (QS) system. Additionally, we also found that exposure to PS-NPs enhanced bacterial antibiotic resistance, posing a challenge to antimicrobial therapy. Our study reveals the toxic effects of nanoplastics and the defense mechanisms of bacteria, which has important implications for the risk assessment and management of environmental nanoplastics.