ABSTRACT

Stressors like metals or antibiotics can affect bacterial community permissiveness for plasmid uptake, but there is little knowledge about long-term effects of such stressors on the evolution of community permissiveness. We assessed the effect of more than 90 years of soil Cu contamination on bacterial community permissiveness (i.e. uptake ability) toward a gfp-tagged IncP-1 plasmid (pKJK5) introduced via an Escherichia coli donor. Plasmid transfer events from the donor to the recipient soil bacterial community were quantified and transconjugants were subsequently isolated by fluorescence activated cell sorting and identified by 16S rRNA gene amplicon sequencing. Transfer frequency of plasmid pKJK5 was reduced in bacterial communities extracted from highly Cu contaminated (4526 mg kg⁻¹) soil compared to corresponding communities extracted from moderately (458 mg kg⁻¹) Cu contaminated soil and a low Cu reference soil (15 mg kg⁻¹). The taxonomic composition of the transconjugal pools showed remarkable similarities irrespective of the degree of soil Cu contamination and despite contrasting compositions of the extracted recipient communities and the original soil communities. Permissiveness assessed at the level of individual operational taxonomic units (OTUs; 16S rRNA gene 97% sequence similarity threshold) was only slightly affected by soil Cu level and high replicate variability of OTU-level permissiveness indicated a role of stochastic events in IncP-1 plasmid transfer or strain-to-strain permissiveness variability.

中文翻译：

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在一系列土壤铜污染中，土壤细菌类群的一个聚合子集对IncP-1质粒pKJK5而言是允许的

摘要

金属或抗生素等应激源可影响细菌对质粒吸收的社区允许性，但对此类应激源对社区允许性演变的长期影响知之甚少。我们评估了超过90年的土壤铜污染对通过大肠杆菌供体引入的带有gfp标签的IncP-1质粒（pKJK5）的细菌群落通透性（即吸收能力）的影响。定量了从供体到受体土壤细菌群落的质粒转移事件，随后通过荧光激活的细胞分选法分离了转接合子，并通过16S rRNA基因扩增子测序进行了鉴定。从高铜污染（4526 mg / kg）提取的细菌群落中，质粒pKJK5的转移频率降低^-1）土壤与从中度（458 mg kg ^-1）的Cu污染土壤和低Cu参考土壤（15 mg kg ^-1）提取的相应群落相比。无论土壤铜污染的程度如何，尽管提取出的受体群落和原始土壤群落的成分形成对比，跨接合池的生物分类组成仍显示出显着的相似性。在各个操作分类单位（OTU； 16S rRNA基因97％序列相似性阈值）水平上评估的介导性仅受土壤铜水平的轻微影响，OTU介导性的高重复变异性表明IncP-1质粒中随机事件的作用传递或应变对应变的允许变异性。