How nanoscale plastics facilitate the evolution of antibiotic resistance?

The plastic can enhance the proliferation of antibiotic resistance genes (ARGs), however, the effect of nanoplastics (NPLs) on bacterial antibiotic resistance has not been clearly explained. Herein, we explored the effects and mechanisms of NPLs of different sizes (200 and 600 nm) on the evolution of antibiotic resistance in Serratia marcescens. The results indicated that the evolution of bacterial antibiotic resistance could be promoted under NPLs exposure, which the median of relative abundance of ARGs was 1.11-1.46 times compared to the treatment without NPLs. Transcriptomic analysis showed that the larger size of NPLs mainly increased the permeability of bacterial cell membranes to efflux antibiotics, thus potentiating antibiotic resistance. While, the smaller NPLs is more than that, its enhanced the expression of antibiotic resistance by modulating bacterial metabolic processes. The genome SNP analysis found that the NPLs could cause the genetic mutation occurrence to alter the membrane transport and metabolism processes, and it increased at a size of 200 nm more than at 600 nm NPLs. Importantly, we demonstrated that the horizontal transfer of ARGs was augmented due to the NPLs could dock to bacterial surface proteins and pull their movement to contact with other bacteria (binding energy of membrane proteins:-8.54 kcal/mol), especially the smaller size. It suggests that NPLs will also contribute to the proliferation of ARGs in the environment. This study provides data for understanding the risk of bacterial resistance.