Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen , Thorvaldsensvej 40, 1871 Frederiksberg, Denmark.
College of Natural Resources and Environment, Fujian Agriculture and Forestry University , Fuzhou, Fujian 350002, China.
Environ Sci Technol. 2017 Mar 7;51(5):3040-3047. doi: 10.1021/acs.est.6b05342. Epub 2017 Feb 23.
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 [H]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) and Zn (≥264 mg kg) but not in soil spiked with unrealistically high levels of tetracycline (up to 100 mg kg). 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.
环境选择抗生素抗性可能是由抗生素残留或共选择剂引起的。本研究采用严格控制的实验设计，比较了金属（铜或锌）和四环素对细菌群落中四环素抗性的（共）选择能力。通过向农业土壤中添加已知水平的铜、锌或四环素来建立土壤微宇宙，这些抗生素和金属通常用于养猪。使用[H]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，而通过一组全细胞细菌生物传感器定量测定土壤铜、锌和四环素的暴露情况。在含有环境相关水平铜（≥365mg/kg）和锌（≥264mg/kg）的土壤中，四环素抗性显著增加，但在添加不合理高浓度四环素（高达 100mg/kg）的土壤中没有增加。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性，而四环素只是暂时具有生物利用性。群落水平的四环素抗性与初始毒性诱导的细菌生长抑制有关。总之，本研究表明，在某些情况下，有毒金属对环境选择抗生素抗性的选择压力可能比特定抗生素本身更强。
