摘要
      微塑料在污水污泥中的保留越来越受到关注，污水污泥是抗生素抗性基因（ARGs）和可移动遗传元件（MGEs）的蓄水池。然而，在污泥的嗜热厌氧消化过程中，聚乙烯微塑料（PE-MP）对ARGs和MGEs命运的影响远未完全理解。本研究表明，在50、100和200个颗粒/g-TS的浓度下，尺寸为40–48µm的PE-MP可以增加ARGs的总丰度。同时，PE-MP浓度与总MGEs含量呈显著正相关（r=0.96，p<0.05）。微生物分析显示，一些功能属在PE-MP胁迫下富集，可能是ARGs和MGEs的潜在宿主。当PE-MP含量从0增加到200个颗粒/g-TS时，产乙酰菌的相对丰度从27.60%增加到32.80%，水解菌的相对富集度增加到28.03%。随后通过共现网络确定了潜在的宿主，其中一些被确定为病原体。使用冗余分析和相关性分析，观察到PE-MP、ARGs和MGE之间的强正相关性。此外，结构方程模型表明了PE-MP对ARGs和MGE丰度的直接和间接影响。MGE可以直接加强ARG的获取和传播。总之，我们的研究结果揭示了PE-MP对污泥AD过程中ARGs和MGE传播的贡献，这可能对人类健康构成风险，应在污水污泥处理过程中予以考虑。
Abstract
The retention of microplastics in sewage sludge, a reservoir of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs), has attracted increasing attention. However, the impact of polyethylene microplastics (PE-MP) on the fate of ARGs and MGEs is far from fully understood in sewage sludge's thermophilic anaerobic digestion process (AD). The present study demonstrated that PE-MP with the size of 40–48 µm at concentrations of 50, 100, and 200 particles/g-TS could enlarge total ARGs abundance. Meanwhile, a significant positive (r = 0.96, p < 0.05) correlation was observed between PE-MP concentration and total MGEs content. Microbial analysis revealed the enrichment of some functional genus under the stress of PE-MP, which might be the potential host of ARGs and MGEs. The relative abundance of acetogens Thermoanaerobacter increased from 27.60 % to 32.80 % and hydrolytic bacteria Caldicoprobacter enriched by 28.03 % when PE-MP content increased from zero to 200 particles/g-TS. The potential hosts were subsequently identified through co-occurrence networks, some of which were identified as pathogens. Strong positive correlations between PE-MP, ARGs, and MGEs were observed using redundancy analysis and correlation analysis. Additionally, the structural equation model indicated the direct and indirect influence of PE-MP on the abundance of ARGs and MGEs. MGEs could enhance the acquisition and dissemination of ARGs directly. Taking together, our findings deciphered the contribution of PE-MP to the spread of ARGs and MGEs in the sludge AD process, which might pose risks to human health and should be considered during sewage sludge disposal.

https://www.sciencedirect.com/science/article/pii/S1385894722049993