Nanoscale polystyrene intensified the microbiome perturbation and antibiotic resistance genes enrichment in soil and Enchytraeus crypticus caused by tetracycline

Abstract

Defined as plastic debris with size of 1–1000 nm, nanoplastics might be potentially more hazardous than plastics with larger size. However, current studies of nanoplastics in terrestrial systems are still limited, especially for the understanding of the combined effects of nanoplastics and antibiotics on microbiome and antibiotic resistance genes (ARGs) in soil invertebrates under the agricultural soil ecosystem is largely unknown. Here, we used Enchytraeus crypticus as model species to study the effects of nanoscale polystyrene and tetracycline. We found that co-exposure to nanoscale polystyrene and tetracycline not only significantly lowered the reproduction rate and increased the body weight of E. crypticus, but also significantly decreased the microbial alpha diversity and disturbed the beta diversity of microbiome in agricultural soil and E. crypticus. Nanoscale polystyrene had limited impacts on soil microbiota either at phylum level or family level but significantly disturbed the microbiome of E. crypticus. More specifically, NPs mainly decreased the relative proportion of rare taxa rather than the dominant phyla, including Acidobacteria (from 2.66% to 0.57%), Chloroflexi (from 1.43% to 0.21%), and Gemmatinomades (from 0.69% to 0.07%) in E. crypticus. Furthermore, synergistic effects for microbiome in soil and E. crypticus were found with nanoscale polystyrene and tetracycline. Meanwhile, nanoscale polystyrene enhanced the toxicity of tetracycline and promoted the enrichment of ARGs, such as multidrug ARGs in soil, and Vancomycin ARGs, Tetracycline ARGs, MLSB ARGs and Chloramphenicol ARGs in E. crypticus. These results add to our understanding of the combined effects of nanoplastics and antibiotics on the microbiome and ARGs of soil invertebrates.