Nanopesticide risk assessment based on microbiome profiling – Community structure and functional potential as biomarkers in captan@ZnO35–45 nm and captan@SiO2 20–30 nm treated orchard soil

Nanoformulation should minimise the usage of pesticides and limit their environmental footprint. The risk assessment of two nanopesticides with fungicide captan as an active organic substance and ZnO35–45 nm or SiO2 20–30 nm as nanocarriers was evaluated using the non-target soil microorganisms as biomarkers. The first time for that kind of nanopesticides next-generation sequencing (NGS) of bacterial 16 S rRNA and fungal ITS region and metagenomics functional predictions (PICRUST2) was made to study structural and functional biodiversity. During a 100-day microcosm study in soil with pesticide application history, the effect of nanopesticides was compared to pure captan and both nanocarriers. Nanoagrochemicals affected microbial composition, especially Acidobacteria-6 class, and alpha diversity, but the observed effect was generally more substantial for pure captan. As for beta diversity, the negative impact was detected only in response to captan and still observed on day 100. Fungal community in the orchard soil showed only a decrease in phylogenetic diversity in captan set-up since day 30. PICRUST2 analysis confirmed several times lower impact of nanopesticides considering the abundance of functional pathways and genes encoding enzymes. Furthermore, the overall data indicated that using SiO2 20–30 nm as a nanocarrier speeds up a recovery process compared to ZnO35–45 nm.