Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn-Institut, Federal Research Centre for Cultivated Plants (JKI) Braunschweig, Germany.
Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn-Institut, Federal Research Centre for Cultivated Plants (JKI) Braunschweig, Germany ; Institute of Environmental and Sustainable Chemistry, Technische Universität Braunschweig Braunschweig, Germany.
Front Microbiol. 2014 Jan 17;4:420. doi: 10.3389/fmicb.2013.00420. eCollection 2013.
Class 1 integrons contribute to the emerging problem of antibiotic resistance in human medicine by acquisition, exchange, and expression of resistance genes embedded within gene cassettes. Besides the clinical setting they were recently reported from environmental habitats and often located on plasmids and transposons, facilitating their transfer and spread within bacterial communities. In this study we aimed to provide insights into the occurrence of genes typically associated with the class 1 integrons in previously not studied environments with or without human impact and their association with IncP-1 plasmids. Total community DNA was extracted from manure-treated and untreated soils, lettuce and potato rhizosphere, digestates, and an on-farm biopurification system and screened by PCR with subsequent Southern blot hybridization for the presence of the class 1 integrase gene intI1 as well as qacE and qacEΔ 1 resistance genes. The results revealed a widespread dissemination of class 1 integrons in the environments analyzed, mainly related to the presence of qacEΔ 1 genes. All 28 IncP-1ε plasmids carrying class 1 integrons, which were captured exogenously in a recent study from piggery manure and soils treated with manure, carried qacEΔ 1 genes. Based on the strong hybridization signals in the rhizosphere of lettuce compared to the potato rhizosphere, the abundances of intI1, qacE/qacEΔ 1, and sul1 genes were quantified relative to the 16S rRNA gene abundance by real-time PCR in the rhizosphere of lettuce planted in three different soils and in the corresponding bulk soil. A significant enrichment of intI1 and qacE/qacEΔ 1 genes was confirmed in the rhizosphere of lettuce compared to bulk soil. Additionally, the relative abundance of korB genes specific for IncP-1 plasmids was enriched in the rhizosphere and correlated to the intI1 gene abundance indicating that IncP-1 plasmids might have contributed to the spread of class 1 integrons in the analyzed soils.
1 类整合子通过基因盒内抗性基因的获取、交换和表达，导致人类医学中抗生素耐药性问题日益严重。除了临床环境外，它们最近还被报道存在于环境栖息地，并且经常位于质粒和转座子上，这促进了它们在细菌群落中的转移和传播。在这项研究中，我们旨在深入了解以前未研究过的人类影响环境和无人类影响环境中与 1 类整合子相关的基因的发生情况，以及它们与 IncP-1 质粒的关系。从粪便处理和未处理的土壤、生菜和土豆根际、消化物以及农场生物净化系统中提取总社区 DNA，并通过 PCR 进行筛选，随后进行 Southern 印迹杂交，以检测 1 类整合酶基因 intI1 以及 qacE 和 qacEΔ1 抗性基因的存在。结果表明，1 类整合子在分析的环境中广泛传播，主要与 qacEΔ1 基因的存在有关。在最近的一项研究中，从猪圈粪便和用粪便处理的土壤中捕获的 28 个携带 1 类整合子的 IncP-1ε 质粒都携带 qacEΔ1 基因。基于生菜根际与土豆根际相比，intI1、qacE/qacEΔ1 和 sul1 基因的杂交信号较强，通过实时 PCR 定量了在三种不同土壤中种植的生菜根际和相应的土壤中 16S rRNA 基因丰度相对的 intI1、qacE/qacEΔ1 和 sul1 基因的丰度。与对照土壤相比，生菜根际中 intI1 和 qacE/qacEΔ1 基因显著富集。此外，IncP-1 质粒特有的 korB 基因的相对丰度在根际中富集，并与 intI1 基因丰度相关，表明 IncP-1 质粒可能有助于分析土壤中 1 类整合子的传播。
