摘要

由于共同或交叉抗性机制，金属抗性与抗生素抗性相关。在这里，筛选了用有机废物处理的金属污染的矿山土壤中的移动遗传元素（MGEs）的存在。通过PCR和Southern印迹杂交证实了缀合的IncP-1和可动员的IncQ质粒以及1类整合子的出现，表明来自这些土壤的细菌具有基因动员能力，其对抗性因子的传播具有影响。此外，通过使用大肠杆菌作为受体，在抗生素选择压力下尝试从土壤细菌群体中外源性分离MGE。基于增加的抗生素抗性鉴定了17种推定的转接合子。研究了推定的转接合子的代谢性状和金属抗性，并对其中两个进行了全基因组测序。大多数推定的转接合子显示出广谱抗生素的多重耐药表型。他们还展示了代谢不同碳源，RNA：DNA比率，生长速率和生物膜形成能力的变化。推定的转接合子的基因组测序未能检测到通过水平基因转移获得的基因，而是揭示了许多无义突变，包括在ubiH中，其失活与观察到的对氨基糖苷类的抗性相关。我们的结果证实，矿井土壤含有编码抗生素抗性的MGE。此外，他们指出了自发突变在短时间内实现低水平抗生素抗性的作用，这与代谢特定碳源的能力之间的权衡有关。

Metal resistance has been associated with antibiotic resistance due to co- or cross-resistance mechanisms. Here, metal contaminated mine soil treated with organic wastes was screened for the presence of mobile genetic elements (MGEs). The occurrence of conjugative IncP-1 and mobilizable IncQ plasmids, as well as of class 1 integrons, was confirmed by PCR and Southern blot hybridization, suggesting that bacteria from these soils have gene-mobilizing capacity with implications for the dissemination of resistance factors. Moreover, exogenous isolation of MGEs from the soil bacterial community was attempted under antibiotic selection pressure by using Escherichia coli as recipient. Seventeen putative transconjugants were identified based on increased antibiotic resistance. Metabolic traits and metal resistance of putative transconjugants were investigated, and whole genome sequencing was carried out for two of them. Most putative transconjugants displayed a multi-resistant phenotype for a broad spectrum of antibiotics. They also displayed changes regarding the ability to metabolise different carbon sources, RNA: DNA ratio, growth rate and biofilm formation. Genome sequencing of putative transconjugants failed to detect genes acquired by horizontal gene transfer, but instead revealed a number of nonsense mutations, including in ubiH, whose inactivation was linked to the observed resistance to aminoglycosides. Our results confirm that mine soils contain MGEs encoding antibiotic resistance. Moreover, they point out the role of spontaneous mutations in achieving low-level antibiotic resistance in a short time, which was associated with a trade-off in the capability to metabolise specific carbon sources.

https://www.sciencedirect.com/science/article/pii/S0048969717332795