Titanium dioxide nanoparticles (TiO₂ NPs) are increasingly utilized in agricultural applications due to their potential benefits in enhancing crop growth and protecting against pathogens. However, their environmental impact, particularly on soil microbial communities, remains a critical concern. This study investigates how soil heterogeneity—specifically clay content and organic matter (OM)—modulates the effects of TiO₂ NPs on bacterial communities over short- and long-term exposure periods. Four distinct soil types were examined: clay soils with low (clay-LOM) and high (clay-HOM) OM content, and sandy soils with low (sand-LOM) and high (sand-HOM) OM content. Each soil type was exposed to an environmentally relevant concentration of 1 mg/kg TiO₂ NPs, with samples collected after 15 days (short-term) and 60 days (long-term) of incubation.
Enzyme activity assays revealed that TiO₂ NPs significantly impacted dehydrogenase activity only in clay-HOM soil during short-term exposure, where activity decreased by 7.9% compared to controls. In contrast, no significant changes were observed in clay-LOM, sand-LOM, or sand-HOM soils at either time point. After long-term incubation, enzyme activity in all soil types increased, and no differences were detected between TiO₂ NP-treated and control soils, suggesting recovery over time.
Bacterial community diversity analysis showed that TiO₂ NPs reduced alpha diversity in clay-HOM soil during short-term exposure, particularly affecting evenness and phylogenetic diversity. However, this effect diminished after 60 days, indicating adaptation or resilience. Beta diversity analyses using weighted UniFrac distances confirmed that only clay-HOM soil exhibited significant community shifts in response to TiO₂ NPs during short-term exposure, with clear separation between treated and control groups. No such separation was observed in sandy soils, regardless of OM content or exposure duration.
Taxonomic profiling indicated that TiO₂ NPs suppressed key functional taxa such as Acidobacteria and Verrucomicrobia in clay-HOM soil, while promoting Proteobacteria.SSU72 Antibody MedChemExpress These shifts were transient; by day 60, community composition had largely recovered, and no significant differences remained between treatments.Renin Antibody custom synthesis Functional predictions based on PICRUSt2 revealed that pathways related to carbohydrate degradation and biosynthesis were downregulated in clay-HOM soil under short-term exposure but normalized after prolonged incubation.PMID:34886784
Co-occurrence network analysis further demonstrated that the decline in Acidobacteriales and Opitutus taxa correlated strongly with reduced carbohydrate metabolic functions, supporting the hypothesis that TiO₂ NPs disrupt carbon cycling processes in organically rich clay soils. However, these disruptions were not sustained beyond 60 days, underscoring the role of microbial adaptation in overcoming nanoparticle stress.
In conclusion, the ecological impact of TiO₂ NPs on soil bacterial communities is highly dependent on soil heterogeneity. While clay-HOM soils exhibit sensitivity to TiO₂ NPs due to enhanced particle retention and bioavailability, the effects are transient and reversible over time. Sandy soils and clay-LOM soils showed minimal responses, highlighting that both clay fraction and OM content must be considered when assessing nanotoxicity. The findings emphasize that long-term exposure allows microbial communities to adapt, reducing the risk of lasting functional disruption. This underscores the importance of incorporating temporal dynamics and site-specific soil properties into environmental risk assessments for nano-agrochemicals.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com