The effects of different types of micro/nano-plastics on the spread of antibiotic resistance genes in soil-lettuce systems

Abstract

Micro/nanoplastics are ubiquitous and persistent in soils, serving as potential carriers for the dissemination of antibiotic resistance. This study introduced microplastics and nanoplastics of varying types and sizes into loess soil and black soil to investigate their impact on the distribution of antibiotic resistance genes (ARGs) within the soil-lettuce system and identify key driving factors. Results indicated that, compared to nanoplastic additions, microplastic additions more significantly enhanced the propagation of ARGs in the soil-lettuce system, with increases in ARG abundance observed in rhizosphere soil (22.46%–233.15%), lettuce roots (17.22%–284.72%), and leaves (0.26%–1428.58%). Polyethylene particles exhibited a greater capacity to promote the transfer of acrB resistance genes from roots to leaves, showing increases ranging from 3.00 to 13.87 times compared to polypropylene (1.79–4.70 times) and polystyrene (−0.66–4.55 times). Ammonia nitrogen, nitrate nitrogen, organic matter content, and pH were identified as primary factors influencing ARG abundance, with these environmental parameters correlating closely with soil type. Mobile genetic elements and bacterial communities play critical roles in the transformation and migration of ARGs within the soil-lettuce system, while Actinobacteria and Proteobacteria represent key potential hosts for ARGs in soils.