摘要

    质粒驱动的细菌之间的抗生素抗性基因（ARGs）的联合转移促进了抗生素抗性的进化和传播。重金属暴露加速了质粒介导的ARG的联合转移。纳米材料是众所周知的用于去除重金属的吸附剂，具有抵抗耐药细菌/促进ARG联合转移的能力。然而，重金属和纳米材料对质粒介导的ARGs的联合转移的共同作用仍是未知的。在这项研究中，我们调查了同时暴露Cd2 +和纳米Fe2O3对恶臭假单胞菌KT2442质粒RP4向水微生物群落的共轭转移的影响。还研究了细菌细胞膜的通透性，抗氧化酶活性和缀合基因的表达。结果表明，Cd2 +和高浓度纳米Fe2O3（10mg / L和100mg / L）的组合显着增加了RP4质粒的共轭转移频率（p <0.05）。在共暴露于Cd2 +和纳米Fe2O3的处理中检测到最多的转导结合剂，其中大多数被确定为人类病原体。通过Cd2 +和纳米Fe2O3的共同作用，ARG的共轭转移的加剧机制与细胞膜通透性，抗氧化酶活性以及共轭基因mRNA表达水平的提高有关。这项研究证实，同时暴露于Cd2 +和纳米Fe2O3对质粒介导的ARG的联合转移起协同协同作用，强调在对抗抗生素耐药性时应谨慎评估纳米材料和重金属的协同作用。

    Conjunctive transfer of antibiotic resistance genes (ARGs) among bacteria driven by plasmids facilitated the evolution and spread of antibiotic resistance. Heavy metal exposure accelerated the plasmid-mediated conjunctive transfer of ARGs. Nanomaterials are well-known adsorbents for heavy metals removal, with the capability of combatting resistant bacteria/facilitating conjunctive transfer of ARGs. However, co-effect of heavy metals and nanomaterials on plasmid-mediated conjunctive transfer of ARGs was still unknown. In this study, we investigated the effect of the simultaneous exposure of Cd2+ and nano Fe2O3 on conjugative transfer of plasmid RP4 from Pseudomonas putida KT2442 to water microbial community. The permeability of bacterial cell membranes, antioxidant enzyme activities and conjugation gene expression were also investigated. The results suggested that the combination of Cd2+ and high concentration nano Fe2O3 (10 mg/L and 100 mg/L) significantly increased conjugative transfer frequencies of RP4 plasmid (p < 0.05). The most transconjugants were detected in the treatment of co-exposure to Cd2+ and nano Fe2O3, the majority of which were identified to be human pathogens. The mechanisms of the exacerbated conjugative transfer of ARGs were involved in the enhancement of cell membrane permeability, antioxidant enzyme activities, and mRNA expression levels of the conjugation genes by the co-effect of Cd2+ and nano Fe2O3. This study confirmed that the simultaneous exposure to Cd2+and nano Fe2O3 exerted a synergetic co-effect on plasmid-mediated conjunctive transfer of ARGs, emphasizing that the co-effect of nanomaterials and heavy metals should be prudently evaluated when combating antibiotic resistance.

    https://www.sciencedirect.com/science/article/pii/S0160412021000787