摘要
      农药经常污染淡水水体，影响水生食物网下的微生物群落。例如，草甘膦除草剂具有间接选择抗生素抗性细菌的潜力。如果相同的基因（例如编码外排泵）对草甘膦和抗生素都具有耐药性，则可能发生这种交叉选择。为了测试天然水生细菌群落的交叉抗性，我们在1000升充满原始湖泊水的中生态系统中添加了草甘膦除草剂（GBH）。57岁以上 天，我们用霰弹枪宏基因组测序和注释宏基因组组装基因组（MAG）追踪了细菌群落的变化，以确定草甘膦靶向酶（烯醇丙酮酸-莽草酸-3-磷酸合成酶；EPSPS）中是否存在已知的抗生素耐药性基因（ARGs）、质粒和耐药性突变。我们发现高剂量的GBH显著增加了ARG的频率，尤其是被选择用于多药外排泵。高剂量GBH后MAG的相对丰度是可预测的，这是基于其基因组中ARG的数量（解释了17%的变异），并且在较小程度上是通过EPSPS中的抗性突变。总之，这些结果表明，GBH可以在天然淡水细菌中交叉选择抗生素耐药性。
ABSTRACT
Agrochemicals often contaminate freshwater bodies, affecting microbial communities that underlie aquatic food webs. For example, the herbicide glyphosate has the potential to indirectly select for antibiotic-resistant bacteria. Such cross-selection could occur if the same genes (encoding efflux pumps, for example) confer resistance to both glyphosate and antibiotics. To test for cross-resistance in natural aquatic bacterial communities, we added a glyphosate-based herbicide (GBH) to 1,000-liter mesocosms filled with water from a pristine lake. Over 57 days, we tracked changes in bacterial communities with shotgun metagenomic sequencing and annotated metagenome-assembled genomes (MAGs) for the presence of known antibiotic resistance genes (ARGs), plasmids, and resistance mutations in the enzyme targeted by glyphosate (enolpyruvyl-shikimate-3-phosphate synthase; EPSPS). We found that high doses of GBH significantly increased ARG frequency and selected for multidrug efflux pumps in particular. The relative abundance of MAGs after a high dose of GBH was predictable based on the number of ARGs in their genomes (17% of variation explained) and, to a lesser extent, by resistance mutations in EPSPS. Together, these results indicate that GBHs can cross-select for antibiotic resistance in natural freshwater bacteria.

https://journals.asm.org/doi/full/10.1128/msystems.01482-21