Pristine and sulfidized zinc oxide nanoparticles alter bacterial communities and metabolite profiles in soybean rhizocompartments

A better understanding of bacterial communities and metabolomic responses to pristine zinc oxide manufacture nanoparticles (ZnO MNPs) and its sulfidized product (s-ZnO MNPs), as well as their corresponding Zn ions in rhizocompartments, critical in the plant-microbe interactions, could contribute to the sustainable development of nano-enabled agriculture. In this study, soybean (Glycine max) were cultivated in soils amended with three Zn forms, namely ZnSO4 center dot 7H(2)O, ZnO MNPs and s-ZnO MNPs at 0, 100 and 500 mg center dot kg(-1) for 70 days. Three Zn forms exposures profoundly decreased the bacterial alpha diversity in roots and nodules. High dose (500 mg center dot kg(-1)) groups had a stronger impact on the bacterial beta diversity than lowdose (100mg center dot kg(-1)) groups. In the rhizosphere soil and roots, 500mg center dot kg(-1) of ZnSO4 and s-ZnOMNPs treatments showed the largest shifts in bacterial community structure, respectively. In addition, several significant changed bacterial taxa and metabolites were found at the high dose groups, which were associated with carbon and nitrogen metabolism. PLS-DA plot showed good discrimination in metabolomic profiles of rhizosphere soil and roots between three Zn forms treatments and control. Most metabolic pathways perturbed were closely linked to oxidative stress. Overall, our study indicates either dissolved or nanoparticulate Zn exposure at high dose can drastically affected bacterial communities and metabolite profiles in soybean rhizocompartments.

Automated summary

This study investigated the impact of different forms of zinc exposure on bacterial communities and metabolite profiles in soybean rhizocompartments. Results showed that all three forms of zinc exposure significantly reduced bacterial diversity in roots and nodules, with higher doses having a greater effect. The bacterial community structure in the rhizosphere soil and roots showed the largest shifts at the highest dose of zinc sulfate and sulfidized zinc oxide nanoparticles treatments. Changes in bacterial taxa and metabolites were mainly associated with carbon and nitrogen metabolism. Metabolic pathways perturbed were closely linked to oxidative stress. Overall, this study demonstrates that both dissolved and nanoparticulate forms of zinc exposure at high doses can have a drastic effect on bacterial communities and metabolite profiles in soybean rhizocompartments.