The influence of elevated CO2 on bacterial community structure and its co-occurrence network in soils polluted with Cr2O3 nanoparticles

Abstract Elevated CO2 (eCO2) and nanoparticles release are considered among the most noteworthy global concerns as they may impose negative effects on human health and ecosystem functioning. A mechanistic understanding of their combined impacts on soil microbiota is essential due to the profound eCO2 effect on soil biogeochemical processes. In this study, the impacts of Cr2O3 nanoparticles (nano-Cr2O3) on the activity, structure and co-occurrence networks of bacterial communities under ambient and eCO2 were compared between a clay loam and a sandy loam soil. We showed that eCO2 substantially mitigated nano-Cr2O3 toxicity, with microbial biomass, enzyme activity and bacterial alpha-diversity in clay loam soil were much higher than those in sandy loam soil. Nano-Cr2O3 addition caused an increase in alpha-diversity except for clay loam soil samples under eCO2. 16S rRNA gene profiling data found eCO2 remarkably reduced community divergences induced by nano-Cr2O3 more efficiently in clay loam soil (P