Differential Impacts of Nanoparticle Formulation on Plant Growth and Soil Bacterial Communities

摘要

While nanoparticles (NPs) are finding utility in many industries, their impacts on ecosystems and human health remains to be fully explored. Still, it is known that NPs have unique properties not observed in bulk materials and some are known to exhibit antimicrobial properties. Microbiomes are not only key to healthy ecosystems but are also intricately connected to the health of multicellular organisms including plants. Some studies have characterized the impact of NPs on seedling growth in defined culture media, but little is known about their effects in complex natural environments such as soil. The goal of this study was to assess the potential effects of different nanoparticle formulations on seed germination, seedling growth and on soil microbial communities. The model used was the germination and growth of Phaseolus vulgaris and polyvinylpyrrolidone (PVP) coated and uncoated Cu2O, Fe3O4 and Ag2O NPs. Seed imbibition was conducted with nanopure H2O containing different amounts of NPs (0.5, 2.5 & 12.5 mg/ml) then planted in commercial potting soil. The higher amounts of PVP-coated and non-coated Fe3O4 NP decreased seed germination rate. All NP formulations decreased biomass accumulation while both PVP-coated and non-coated Ag2O NPs significantly decreased plant growth at 12.5 mg/ml. Overall, the measured plant growth parameters were impacted by NP treatments particularly the addition of Fe3O4 and Ag2O NPs at higher concentrations. Using two experimental approaches (quantitative PCR and 16S rRNA gene sequencing), effects of the NPs on soil bacterial communities were examined. Alterations in the soil bacterial community composition structure and richness was demonstrated. Bacterial richness was significantly reduced after 30 days of exposure. Particularly, Cu2O and Ag2O NPs caused a shift in class and phyla composition. While the mechanisms of these observations remain to be elucidated, it is proposed that the known antimicrobial properties of NPs and the potential release of ions resulted in differential reduced growth and death of bacteria phyla.