Alteration of Soil Bacteriome by Prolonged Exposure to Metal Oxide Nanoparticles

Metal oxide nanoparticles (MONPs) have found applications in many industrial and consumer products and are inevitably released into the environment, including soil. Soils host diverse microorganisms that are integral to ecosystem function including regulating plant growth. In this study, the influence of Cu2O, Fe3O4 and Ag2O NPs on soil microbial communities was assessed. Microbial community diversity and compositional structure was characterized using quantitative PCR and 16S rRNA gene sequencing. MONPs altered soil bacteria community composition by causing significant reduction in bacterial diversity and change in bacterial abundance. Soils with Cu2O and Ag2O NPs treatments significantly reduce bacterial diversity accompanied by shifts at the Class and Phylum taxonomic levels toward bacteria groups responsible for chitin degradation (Bacteriodetes) and nitrogen fixation (alpha-Proteobacteria). Response of bacterial communities to MONPs exposure is dependent on the exposure time and type of MONPs used. While the mechanisms underlying these observations remain to be elucidated, it is proposed that the known antimicrobial properties of Cu2O and Ag2O NPs cause reduced growth and viability of some bacteria taxa.