Polystyrene Nanoplastics Inhibit the Transformation of Tetrabromobisphenol A by the Bacterium Rhodococcus jostii

Microplastics (MPs) and nanoplastics (NPs) in the environment pose significant risks to organisms of different trophic levels. While the toxicity of MPs and NPs have been extensively investigated, it remains unknown whether these particles affect microbial transformation of organic pollutants. Here, we show that 20 and 100 nm polystyrene NPs (PS-NPs) can inhibit the transformation of tetrabromobisphenol A (TBBPA) by Gram- positive bacterium Rhodococcus jostii in a concentration-dependent manner. We found that smaller PS-NPs were more inhibitory than larger ones and that both PSNPs affected biotransformation in several ways. PS-NPs adsorbed TBBPA on their surface and reduced the bioavailable concentration of TBBPA for transformation by R. jostii. Furthermore, PS-NPs induced oxidative stress, increased membrane permeability, and downregulated O-methyltransferase enzymes that transform TBBPA into their methylated derivatives. Our results demonstrate that PS-NPs can impact microbial transformation of organic pollutants, and these effects should be accounted for in future environmental risk assessments.

Automated summary

The study shows that 20 and 100 nm polystyrene NPs can inhibit the transformation of tetrabromobisphenol A by Gram-positive bacterium Rhodococcus jostii, with smaller particles exhibiting stronger inhibitory effects. PS-NPs adsorb TBBPA on their surface, reducing the bioavailable concentration for transformation, and also induce oxidative stress, affect membrane permeability, and downregulate enzyme activity.