摘要:
环境中广泛存在的抗生素和抗生素抗性基因会导致很严重的人类健康风险。在我们前期研究中发现,离子液体1-丁基-3-甲基咪唑六氟磷酸盐([BMIm] [PF6])作为环境选择性压力可以促进抗生素抗性基因的水平转移。本研究以E. coli DH5α (RP4) 和同属的E. coli HB101,以及E. coli DH5α (RP4)和跨属的Salmonella enterica之间的纯菌接合转移体系为考察对象,从mRNA基因表达调控水平角度阐明离子液体[BMIm] [PF6] (0.001~2.5 g·L-1)影响质粒RP4接合转移的机理。结果表明,离子液体[BMIm] [PF6]通过抑制基因korA, korB和trbA的mRNA表达水平来提高接合和跨膜转运基因trbBp和trfAp的表达;增强水平转移基因的mRNA表达水平,并通过增强负调控基因kilA和kilB的mRNA表达水平抑制质粒的垂直传递过程;通过抑制基因trbK的mRNA表达水平降低接合转移体系的排斥效果,从而促进质粒RP4的接合转移。该结果有助于为抗生素抗性基因在环境中水平转移扩散的机理研究提供理论依据。
Abstract:
Widespread antibiotic and antibiotic resistance genes (ARGs) can pose serious health risks. In our previous study, an ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]) exerted selective pressure promoting the dissemination of ARGs via horizontal gene transfer. To further investigate the molecular mechanisms of an IL [BMIm][PF6] (0.001-2.5 g·L-1) facilitate the conjugative transfer of ARGs with the mRNA expression levels of conjugative transfer genes, plasmid RP4 conjugative transfer were setup from Escherichia coli DH5α (as the donor) to E. coli HB101 (as the recipient, same species) and Salmonella enterica (as the recipient, across genera). Results of the mRNA expression levels of conjugative transfer genes showed that alleviation of the repression of korA, korB, and trbA genes significantly triggered the expression of trbBp and trfAp, promoting the conjugative transfer of plasmid RP4; Enhanced traF mRNA expression levels for facilitating horizontal transfer and increased kilA and kilB mRNA expression levels for inhibiting the genes responsible for vertical transfer; Inhibited trbK mRNA expression levels for decreasing the entry exclusion phenotype, promoting the conjugative transfer of plasmid RP4. It is helpful to provide theoretical basis for the study of the mechanism of ARGs transfer in the environment.
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