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. 2024 Dec 19;12(12):920.
doi: 10.3390/toxics12120920.

Metagenomic Analysis Reveals the Effects of Microplastics on Antibiotic Resistance Genes in Sludge Anaerobic Digestion

Zhonghong Li  1 , Donghai Yuan  1
Affiliations

Metagenomic Analysis Reveals the Effects of Microplastics on Antibiotic Resistance Genes in Sludge Anaerobic Digestion

Zhonghong Li et al. Toxics. .

Abstract

Sewage sludge is recognized as both a source and a reservoir for antibiotic resistance genes (ARGs). Within an anaerobic digestion (AD) system, the presence of microplastics (MPs) has been observed to potentially facilitate the proliferation of these ARGs. Understanding the influence of MPs on microbial behavior and horizontal gene transfer (HGT) within the AD system is crucial for effectively managing the dissemination of ARGs in the environment. This study utilized metagenomic approaches to analyze the dynamics of various types of ARGs and potential microbial mechanisms under exposure to MPs during the AD process. The findings indicated that MPs in the AD process can enhance the proliferation of ARGs, with the extent of this enhancement increasing with the dosage of MPs: polyethylene (PE), polyethylene terephthalate (PET), and polylactic acid (PLA) MPs increased the abundance of ARGs in the anaerobic digestion system by up to 29.90%, 18.64%, and 14.15%, respectively. Additionally, the presence of MPs increased the relative abundance of mobile genetic elements (MGEs) during the AD process. Network correlation analysis further revealed that plasmids represent the predominant category of MGEs involved in the HGT of ARGs. Propionibacterium and Alicycliphilus were identified as the primary potential hosts for these ARGs. The results of gene function annotation indicated that exposure to MPs led to an increased the relative abundance of genes related to the production of reactive oxygen species (ROS), alterations in membrane permeability, ATP synthesis, and the secretion of extracellular polymeric substances (EPS). These genes play crucial roles in influencing the HGT of ARGs.

Keywords: anaerobic sludge digestion; antibiotic resistance genes; horizontal gene transfer; metagenome; microplastics.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
(A) Distribution and (B) proportion of ARGs in AD system with different dosages and types of MPs.
Figure 2
Figure 2
Distribution of ARG subtypes in AD system with different dosages and types of MPs.
Figure 3
Figure 3
Distribution and of MGEs in AD system with different dosages and types of MPs.
Figure 4
Figure 4
Network analysis of the correlation between ARGs and MGEs.
Figure 5
Figure 5
Relative abundance of bacterial community structure at the phylum (A) and genus (B) level in the AD system.
Figure 6
Figure 6
Network analysis of the correlation between ARGs and genus.
Figure 7
Figure 7
Changes in functional genes in AD system with different dosages and types of MPs.
See this image and copyright information in PMC

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