摘要
根际是农业土壤中抗生素抗性基因(ARG)繁殖的关键场所。农药污染在土壤中无处不在,例如毒死rif是最常用的农药之一。然而,关于添加农药后根际土壤中ARGs分布变化和ARGs流行的驱动机制的报道知之甚少。在这项研究中,无论毒死rif的存在如何,小麦根际土壤中ARGs(tetM,tetO,tetQ,tetW,tetX,sul1和sul2)和intI1的丰度都明显高于散装土壤。在第50天和第100天,20.0 mg·kg-1毒死rif分别显着增加了散装土壤中总ARGs和intI1的丰度,但对根际土壤却没有。根际对ARGs的影响远大于毒死rif。第50天的ARGs和intI1丰度高于第100天的C.N比和NO3--N含量(受根际和耕种时间的影响),显着解释了ARGs的增加。与散土相比,根际将四环素抗性基因(TRGs)的宿主细菌intI1移到属水平,而将sul1,sul2的宿主细菌移到了菌落水平。根际简化了ARG,宿主细菌和代谢产物之间的联系。细菌群落在ARGs和intI1的变化中起重要作用,而散装土壤和根际土壤中潜在宿主的分布差异与代谢物的丰度和组成有关。这些结果为了解小麦根际土壤中的ARG,相关细菌群落和代谢产物之间的联系提供了有价值的信息。
Rhizosphere is a crucial site for the proliferation of antibiotic resistance genes (ARGs) in agricultural soil. Pesticide contamination is ubiquitous in soil, such as chlorpyrifos as one of the most commonly used pesticides. However, limited knowledge is reported about ARGs profiles changes and the driving mechanism of ARGs prevalence in rhizosphere soil after adding pesticide. In this study, irrespective of chlorpyrifos presence, the abundances of ARGs (tetM, tetO, tetQ, tetW, tetX, sul1 and sul2) and intI1 in rhizosphere soil of wheat were obviously higher than those in bulk soil. 20.0 mg·kg−1 chlorpyrifos significantly increased the abundance of total ARGs and intI1 in bulk soil, respectively, at day 50 and 100, but not in rhizosphere soil. Rhizosphere influence on ARGs was far greater than chlorpyrifos. ARGs and intI1 abundances were higher at day 50 than ones at day 100. C/N ratio and NO3−-N content, which were affected by rhizosphere and cultivation time, significantly explained the increased ARGs. Compared to bulk soil, rhizosphere shifted host bacteria of tetracycline resistance genes (TRGs), intI1 at genus level, and host bacteria of sul1, sul2 at phylum level. Rhizosphere simplified the linkage of ARGs, host bacteria and metabolites. Bacterial communities played important roles in the variation of ARGs and intI1, and the difference in the distribution of potential hosts between bulk and rhizosphere soil was related to metabolites abundance and composition. These results provide valuable information for understanding the linkage of ARGs, associated bacteria communities and metabolites in the wheat rhizosphere soil.
https://www.sciencedirect.com/science/article/abs/pii/S0048969720339796