摘要

       细菌中的重金属抗性基因（MRGs）和抗生素抗性基因（ARGs）可以响应重金属的诱导。然而，在长期重金属污染区域中，MRGs 和 ARGs 的共存仍然知之甚少。在这里，我们调查了中国北方铜尾矿坝区土壤细菌 MRGs、ARGs 丰度与重金属污染之间的关系。我们发现分别编码对砷和大环内酯的抗性机制的 arsC 和 ereA 基因是研究区中最丰富的 MRG 和 ARG。 MRGs 的丰度与镉 (Cd) 浓度呈正相关，这表明 Cd 在 MRGs 选择中的重要性。网络分析结果表明，sulII和MRGs共存，copB与ARGs同时发生，表明MRGs和ARGs在重金属污染的土壤中可以共选。网络分析还揭示了 Cd 和 MRGs 的共存，因此具有高“毒性反应”因子的重金属可以用作 MRGs 的指标。该研究提高了对细菌耐药性与多金属污染之间关系的理解，并为探索微生物在多金属污染环境中的适应机制奠定了基础。

       Heavy metal resistance genes (MRGs) and antibiotic resistance genes (ARGs) in bacteria can respond to the inducement of heavy metals. However, the co-occurrence of MRGs and ARGs in the long-term heavy metal contaminated area is still poorly understood. Here, we investigated the relationship between the abundance of soil bacteria MRGs, ARGs and heavy metal pollution in a copper tailing dam area of northern China. We found that arsC and ereA genes coding for resistance mechanisms to arsenic and to macrolides, respectively, are the most abundant MRG and ARG in the study area. The abundance of MRGs is positively correlated with cadmium (Cd) concentration, and this indicates the importance of Cd in the selection of MRGs. The network analysis results show that sulII and MRGs co-occur and copB occur with ARGs, which suggests that MRGs and ARGs can be co-selected in the soil contaminated by heavy metal. The network analysis also reveals the co-occurrence of Cd and MRGs, and thus heavy metal with a high ‘toxic-response’ factor can be used as the indicator of MRGs. This study improves the understanding of the relationship between bacterial resistance and multi-metal contamination, and underlies the exploration of the adaptive mechanism of microbes in the multi-metal contaminated environment.

https://www.frontiersin.org/articles/10.3389/fmicb.2019.01916/full