Trophic Transfer of Antibiotic Resistance Genes in a Soil Detritus Food Chain

The presence and spread of antibiotic resistance genes (ARGs) are causing substantial global public concern; however, the dispersal of ARGs in the food chain is poorly understood. Here, we experimented with a soil collembolan (Folsomia candida)-predatory mite (Hypoaspis aculeifer) model food chain to study trophic transfer of ARGs in a manure-contaminated soil ecosystem. Our results showed that manure amendment of soil could significantly increase ARGs in the soil collembolan microbiome. With the ARGs in the prey collembolan microbiome increasing, an increase in ARGs in the predatory mite microbiome was also observed, especially for three high abundant ARGs (blaSHV, fosX and aph6ia). Three unique ARGs were transferred into the microbiome of the predatory mite from manure amended soil via the prey collembolan (aac(6')-lb(akaaacA4), yidY_mdtL and tolC). Manure amendment altered the composition and structure and reduced the diversity of the microbiomes of the prey collembolan and the predatory mite. We further reveal that bacterial communities and mobile genetic elements were two important drivers for the trophic transfer of ARGs, not just for ARGs distribution in the samples. These findings suggest that the importance of food chain transmission of ARGs for the dispersal of resistance genes in soil ecosystems may be underestimated.