Julius Kühn-Institut - Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11-12, 38104 Braunschweig, Germany.
Technische Universität Braunschweig, Institut für Ökologische und Nachhaltige Chemie, Hagenring 30, 38106 Braunschweig, Germany.
FEMS Microbiol Ecol. 2018 Feb 1;94(2). doi: 10.1093/femsec/fix145.
Veterinary antibiotics, bacteria carrying antibiotic resistance determinants located on mobile genetic elements and nutrients are spread on agricultural soil using manure as fertilizer. However, systematic quantitative studies linking antibiotic concentrations and antimicrobial resistance genes (ARGs) in manure and the environment are scarce but needed to assess environmental risks. In this microcosm study, a sandy and a loamy soil were mixed with manure spiked with streptomycin or doxycycline at five concentrations. Total-community DNA was extracted on days 28 and 92, and the abundances of ARGs (aadA, strA, tet(A), tet(M), tet(W), tet(Q), sul1, qacE/qacEΔ1) and class 1 and 2 integron integrase genes (intI1 and intI2) were determined by qPCR relative to 16S rRNA genes. Effects on the bacterial community composition were evaluated by denaturing gradient gel electrophoresis of 16S rRNA gene amplicons. Manure application to the soils strongly increased the relative abundance of most tested genes. Antibiotics caused further enrichments which decreased over time and were mostly seen at high concentrations. Strikingly, the effects on relative gene abundances and soil bacterial community composition were more pronounced in sandy soil. The concept of defining antibiotic threshold concentrations for environmental risk assessments remains challenging due to the various influencing factors.
兽用抗生素、携带位于移动遗传元件上的抗生素抗性决定簇的细菌以及营养物质，通过粪肥作为肥料施用于农业土壤。然而，将抗生素浓度与抗微生物药物抗性基因（ARGs）在粪肥和环境中的联系进行系统定量研究的情况很少，但这是评估环境风险所必需的。在本微宇宙研究中，将沙质土壤和粘质土壤与经链霉素或强力霉素五种浓度处理的粪肥混合。在第 28 天和第 92 天提取总群落 DNA，并通过 qPCR 相对于 16S rRNA 基因确定 ARGs（aadA、strA、tet(A)、tet(M)、tet(W)、tet(Q)、sul1、qacE/qacEΔ1）和类 1 和 2 整合子整合酶基因（intI1 和 intI2）的丰度。通过 16S rRNA 基因扩增子的变性梯度凝胶电泳评估对细菌群落组成的影响。将粪肥施用于土壤中，强烈增加了大多数测试基因的相对丰度。抗生素引起了进一步的富集，随着时间的推移而减少，并且主要在高浓度下可见。引人注目的是，粪肥对相对基因丰度和土壤细菌群落组成的影响在沙质土壤中更为明显。由于各种影响因素，定义环境风险评估中抗生素阈值浓度的概念仍然具有挑战性。
