摘要

        抗生素抗性的环境选择可能由抗生素残留物或选择剂引起。使用严格控制的实验设计，我们比较了金属（Cu或Zn）和四环素与（共）选择细菌群落中四环素抗性的能力。通过修改已知水平的Cu，Zn或四环素农业土壤来建立土壤微观世界，所述Cu，Zn或四环素代表了养猪常用金属和抗生素。采用[ 3H ]亮氨酸掺入技术测定土壤细菌生长动态和细菌群落水平的四环素抗性，而土壤Cu、Zn和四环素暴露量由一组全细胞细菌生物反应器定量。在含有环境相关水平Cu (≥365 mg·kg - 1 )和Zn (≥264 mg·kg - 1 )的土壤中，四环素抗性显著增加，但在土壤中添加不符合实际的高浓度四环素(高达100 mg·kg - 1 )，四环素抗性没有显著增加。这些观察结果与生物传感器数据一致，表明金属仍然具有生物利用度，而四环素仅具有短暂的生物利用度。社区级四环素抗性与初始毒物诱导的细菌生长抑制相关。总之，我们的研究表明，在某些情况下，有毒金属对抗生素抗性的环境选择的选择压力可能比施加特定抗生素本身更大。

Environmental selection of antibiotic resistance may be caused by either antibiotic residues or coselecting agents. Using a strictly controlled experimental design, we compared the ability of metals (Cu or Zn) and tetracycline to (co)select for tetracycline resistance in bacterial communities. Soil microcosms were established by amending agricultural soil with known levels of Cu, Zn, or tetracycline known to represent commonly used metals and antibiotics for pig farming. Soil bacterial growth dynamics and bacterial community-level tetracycline resistance were determined using the [3H]leucine incorporation technique, whereas soil Cu, Zn, and tetracycline exposure were quantified by a panel of whole-cell bacterial bioreporters. Tetracycline resistance increased significantly in soils containing environmentally relevant levels of Cu (≥365 mg kg–1) and Zn (≥264 mg kg–1) but not in soil spiked with unrealistically high levels of tetracycline (up to 100 mg kg–1). These observations were consistent with bioreporter data showing that metals remained bioavailable, whereas tetracycline was only transiently bioavailable. Community-level tetracycline resistance was correlated to the initial toxicant-induced inhibition of bacterial growth. In conclusion, our study demonstrates that toxic metals in some cases may exert a stronger selection pressure for environmental selection of resistance to an antibiotic than the specific antibiotic itself.

https://pubs.acs.org/doi/abs/10.1021/acs.est.6b05342