Exposure of a Soil Collembolan to Ag Nanoparticles and AgNO3 Disturbs Its Associated Microbiota and Lowers the Incidence of Antibiotic Resistance Genes in the Gut.

Gut microbiota contribute to host health. Numerous recent studies have focused on the survival and reproduction of nontarget soil animals exposed to the toxicity of silver nanoparticles (AgNPs) but changes in the gut microbiota due to nanoparticle toxicity are largely unknown. Here, we examine some effects of AgNPs and silver nitrate (ionic Ag) on the gut microbiota of the common soil collembolan Folsomia candida using Illumina sequencing and concomitant changes in antibiotic resistance genes (ARGs) of the gut microbiota using high-throughput quantitative PCR. A large number of Ag accumulated in Ag-exposed individuals after 28 days and ionic Ag significantly inhibited the reproduction of the collembolan (by 19.3%). Exposure to AgNPs disturbed the composition of the collembolan gut bacterial community, resulting in dysbiosis of the gut microbiota. However, the dominant microbiota was shared among different treatments. In addition, AgNPs exposure did indeed reduce the incidence of ARGs in the collembolan gut microbiota. A weak relationship was identified between gut bacterial communities and ARG profiles. These results extend our knowledge regarding the role of the gut microbiota in assessing the soil ecotoxicology of AgNPs.