Impact of TiO<sub>2</sub> and ZnO Nanoparticles on Soil Bacteria and the Enantioselective Transformation of Racemic-Metalaxyl in Agricultural Soil with <i>Lolium perenne</i>: A Wild Greenhouse Cultivation
Qing Zhou, Xu Zhang, Zhong Wu
Abstract
The effects of TiO 2 and ZnO nanoparticles on soil bacteria and enantioselective transformation of racemic-metalaxyl ( rac -metalaxyl) in agricultural soil with or without Lolium perenne were investigated in an outdoor greenhouse. After a 70-day exposure to 2‰ ZnO, microbial biomass carbon decreased by 66% and bacterial community composition significantly changed. Meanwhile, ZnO decreased chlorophyll cumulation in L. perenne by 34%. ZnO also inhibited the enantioselective transformation of metalaxyl enantiomers and changed the enantiomer fraction of metalaxyl. TiO 2 showed similar effects but to a lesser extent. L. perenne promoted the transformation of rac -metalaxyl and ingested TiO 2 and ZnO. L. perenne changed the bacterial co-occurrence networks and biomarkers in native soil and soil exposed to TiO 2 and ZnO. L. perenne reduced the inhibition effects of TiO 2 and ZnO on the transformation of rac -metalaxyl. The decrease in the relative abundance of soil keystone taxa such as Acidobacteria and Gemmatimonas might respond to the corresponding slow transformation of rac -metalaxyl in soils exposed to TiO 2 and ZnO, regardless of L. perenne . Our results demonstrated the existence of mutual interactions among the impact of engineered nanoparticles on different components (microbes, plants, and coexisting pollutants) in the terrestrial ecosystem.