摘要
      几项研究表明抗生素抗性表型与其他有毒化合物如重金属之间存在密切关系，这些化合物包括共同抗性或交叉抗性机制。宏基因组文库是以前在大肠杆菌中构建的，其DNA从居住在高度被重金属污染的酸性矿山排水（AMD）场地的细菌群落中提取。在这里，我们使用这个以前构建的文库进行了涉及抗生素抗性的基因的搜索。特别是，在携带源自CARN5和CARN2的四个不同基因座的五个克隆中观察到对抗生素的抗性，两个基因组从宏基因组数据重建。在三个CARN2基因座中，两个携带与先前提出参与抗生素抗性的基因同源的基因。第三个CARN2基因座携带编码具有未知功能的膜转运蛋白的基因，并发现其赋予细菌对利福平，庆大霉素和卡那霉素的抗性。 Thiomonas delicata DSM 16361和Thiomonas sp。的基因组。在这项研究中对X19进行了测序。在这些基因组中发现了这三个CARN2基因座上携带的基因的同源物，其中两个基因座在基因组岛中被发现。总之，这些发现证实，受到几种有毒金属污染的AMD环境也构成细菌栖息地，起到抗生素抗性基因储库的作用。

      Several studies have suggested the existence of a close relationship between antibiotic-resistant phenotypes and resistance to other toxic compounds such as heavy metals, which involve co-resistance or cross-resistance mechanisms. A metagenomic library was previously constructed in Escherichia coli with DNA extracted from the bacterial community inhabiting an acid mine drainage (AMD) site highly contaminated with heavy metals. Here, we conducted a search for genes involved in antibiotic resistance using this previously constructed library. In particular, resistance to antibiotics was observed among five clones carrying four different loci originating from CARN5 and CARN2, two genomes reconstructed from the metagenomic data. Among the three CARN2 loci, two carry genes homologous to those previously proposed to be involved in antibiotic resistance. The third CARN2 locus carries a gene encoding a membrane transporter with an unknown function and was found to confer bacterial resistance to rifampicin, gentamycin, and kanamycin. The genome of Thiomonas delicata DSM 16361 and Thiomonassp. X19 were sequenced in this study. Homologs of genes carried on these three CARN2 loci were found in these genomes, two of these loci were found in genomic islands. Together, these findings confirm that AMD environments contaminated with several toxic metals also constitute habitats for bacteria that function as reservoirs for antibiotic resistance genes.

https://link.springer.com/article/10.1007/s11356-017-0535-8