摘要
抽象图像
广泛传播的抗生素耐药性基因（ARGs）已成为公共卫生关注的焦点。转化对于ARGs在土壤和相关环境中的传播至关重要；然而，土壤成分如何促进ARGs转化的机制仍然难以捉摸。在这里，我们证明了三种具有代表性的矿物-腐殖酸（HA）复合物对枯草芽孢杆菌中质粒载体ARGs的转化产生了相反的影响。矿物表面结合的HA促进了高岭石和蒙脱石体系中的转化，同时观察到HA对针铁矿的抑制作用。HA涂层高岭土的转化率升高主要归因于能力刺激因子（CSF）活性的增强，而蒙脱石-HA复合物的转化率增加则归因于鞭毛驱动的细胞运动诱导的DNA吸附亲和力减弱和基因表达增强。在针铁矿系统中，HA通过减轻细胞膜损伤在抑制转化方面发挥着重要作用。所获得的结果为腐殖物质调节土壤矿物细菌转化的不同机制提供了见解。我们的发现将有助于更好地了解ARGs在土壤系统中的命运，并为利用土壤成分，特别是有机物，在一系列环境中减缓ARGs的传播提供潜力。
Abstract
Abstract Image
Widespread antibiotic resistance genes (ARGs) have emerged as a focus of attention for public health. Transformation is essential for ARGs dissemination in soils and associated environments; however, the mechanisms of how soil components contribute to the transformation of ARGs remain elusive. Here we demonstrate that three representative mineral–humic acid (HA) composites exert contrasting influence on the transformation of plasmid-borne ARGs in Bacillus subtilis. Mineral surface-bound HA facilitated transformation in kaolinite and montmorillonite systems, while an inhibitory effect of HA was observed for goethite. The elevated transformation by HA-coated kaolinite was mainly attributed to the enhanced activity of competence-stimulating factor (CSF), while increased transformation by montmorillonite–HA composites was assigned to the weakened adsorption affinity of DNA and enhanced gene expression induced by flagella-driven cell motility. In goethite system, HA played an overriding role in suppressing transformation via alleviation of cell membrane damage. The results obtained offer insights into the divergent mechanisms of humic substances in modulating bacterial transformation by soil minerals. Our findings would help for a better understanding on the fate of ARGs in soil systems and provide potentials for the utilization of soil components, particularly organic matter, to mitigate the spread of ARGs in a range of settings.

https://pubs.acs.org/doi/abs/10.1021/acs.est.2c06410