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Potential environmental risks of field bio/non-degradable microplastic from mulching residues in farmland: Evidence from metagenomic analysis of plastisphere

Journal of Hazardous Materials 2024 33 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Kang Li, Libo Xu, Xinyi Bai, Xinyi Bai, Guangbao Zhang, Mengjun Zhang, Yi Huang

Summary

Researchers analyzed the microbes living on biodegradable and conventional plastic mulch fragments in farm soil and found that both types harbored antibiotic resistance genes and disease-causing bacteria, including human pathogens. Surprisingly, the biodegradable plastic (PBAT/PLA) had a higher diversity and abundance of resistance genes than conventional polyethylene. This challenges the assumption that biodegradable plastics are always safer and raises concerns about antibiotic resistance spreading from farm microplastics.

Polymers

The plastisphere may act as reservoir of antibiotic resistome, accelerating global antimicrobial resistance dissemination. However, the environmental risks in the plastisphere of field microplastics (MPs) in farmland remain largely unknown. Here, antibiotic resistance genes (ARGs) and virulence factors (VFs) on polyethylene microplastics (PE-MPs) and polybutylene adipate terephthalate and polylactic acid microplastics (PBAT/PLA-MPs) from residues were investigated using metagenomic analysis. The results suggested that the profiles of ARG and VF in the plastisphere of PBAT/PLA-MPs had greater number of detected genes with statistically higher values of diversity and abundance than soil and PE-MP. Procrustes analysis indicated a good fitting correlation between ARG/VF profiles and bacterial community composition. Actinobacteria was the major host for tetracycline and glycopeptide resistance genes in the soil and PE-MP plastisphere, whereas the primary host for multidrug resistance genes changed to Proteobacteria in PBAT/PLA-MP plastisphere. Besides, three human pathogens, Sphingomonas paucimobilis, Lactobacillus plantarum and Pseudomonas aeruginosa were identified in the plastisphere. The PE-MP plastisphere exhibited a higher transfer potential of ARGs than PBAT/PLA-MP plastisphere. This work enhances our knowledge of potential environmental risks posed by microplastic in farmland and provides valuable insights for risk assessment and management of agricultural mulching applications.

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