摘要

微生物对抗生素和重金属的抗性常常是相互联系的，这表明微生物在面临重金属胁迫对重金属产生抗性机制的同时，极有可能也会对抗生素产生抗性。然而，长期以来，对重金属引起的抗生素耐药性变化缺乏明确的证据。本研究采用高通量定量PCR方法，研究了两种不同土壤对铜污染( 0～800 mg·kg - 1 )4～5年的抗性基因( ARGs)的反应。共检测到157个和149个独特的ARG，其中多耐药性和β-内酰胺类抗生素抗性基因为主。在红壤的中等铜浓度( 100 - 200 mg·kg - 1 )和潮土的高铜浓度( 400 - 800 mg·kg - 1)下，ARGs的多样性和丰度最高。铜污染土壤中总ARG和几种ARG类型的丰度与可移动遗传原件( MGEs)呈显著正相关，说明ARG在铜污染土壤中具有潜在迁移性。网络分析显示，ARGs与微生物类群之间存在显著的共存关系，表明微生物群落与ARGs之间存在密切关联。结构方程模型表明，铜污染对ARG模式的显著影响主要通过改变微生物群落组成和MGEs实现。结果表明，长期Cu污染显著改变了环境抗生素耐药性的多样性、丰度和潜在迁移性，并提醒人们注意环境中重金属污染传播ARG的风险。

Bacterial resistance to antibiotics and heavy metals are frequently linked, suggesting that exposure to heavy metals might select for bacterial assemblages conferring resistance to antibiotics. However, there is a lack of clear evidence for the heavy metal-induced changes of antibiotic resistance in a long-term basis. Here, we used high-capacity quantitative PCR array to investigate the responses of a broad spectrum of antibiotic resistance genes (ARGs) to 4–5 year copper contamination (0–800 mg kg−1) in two contrasting agricultural soils. In total, 157 and 149 unique ARGs were detected in the red and fluvo-aquic soil, respectively, with multidrug and β-lactam as the most dominant ARG types. The highest diversity and abundance of ARGs were observed in medium copper concentrations (100–200 mg kg−1) of the red soil and in high copper concentrations (400–800 mg kg−1) of the fluvo-aquic soil. The abundances of total ARGs and several ARG types had significantly positive correlations with mobile genetic elements (MGEs), suggesting mobility potential of ARGs in copper-contaminated soils. Network analysis revealed significant co-occurrence patterns between ARGs and microbial taxa, indicating strong associations between ARGs and bacterial communities. Structural equation models showed that the significant impacts of copper contamination on ARG patterns were mainly driven by changes in bacterial community compositions and MGEs. Our results provide field-based evidence that long-term Cu contamination significantly changed the diversity, abundance and mobility potential of environmental antibiotic resistance, and caution the un-perceived risk of the ARG dissemination in heavy metal polluted environments.

http://onlinelibrary.wiley.com/doi/10.1111/1462-2920.13370/full