Integrating metabolomics and high-throughput sequencing to investigate the effects of tire wear particles on mung bean plants and soil microbial communities

Tire wear particles (TWPs) generated by vehicle tires are ubiquitous in soil ecosystems, while their impact on soil biota remains poorly understood. In this study, we investigated the effects of TWPs (0.1%, 0.7%, and 1.5% of dry soil weight) on the growth and metabolism of mung bean (Vigna radiata) plants over 32 days in soil pots. We found that TWPs-treated soils had high levels of heavy metals and polycyclic aromatic hydrocarbons (PAHs). However, there was no significant impact of TWPs exposure on plant growth, suggesting that mung bean plants have a degree of tolerance to TWPs. Despite the lack of impact on plant growth, exposure to TWPs had significant effects on soil enzyme activities, with a decrease of over 50% in urease and dehydrogenase activity. Furthermore, TWPs exposure resulted in marked changes in the plant metabolite profile, including altered levels of sugars, carboxylic acids, and amino acids, indicating altered nitrogen and amino acid-related metabolic pathways. TWPs exposure also disrupted the rhizospheric and bulk soil microbiota, with a decrease in the abundance of bacterial (Blastococcus) and fungal (Chaetomium) genera involved in nitrogen cycles and suppressing plant diseases. In summary, our study provides new insights into the effects of TWPs on plants and soil, highlighting the potential ecological consequences of TWPs pollution in terrestrial ecosystems and underscoring the need for further research in this area.