Soil metabolism and bacterial response to Di(2-ethylhexyl) phthalate (DEHP) stress in Brassica chinensis L. (Shanghai Qing)

Di(2-ethylhexyl) phthalate (DEHP) is a typical endocrine disrupter. Plastic films containing DEHP, widely used in agriculture, have caused severe soil pollution and pose potential risks to human health through the food chain. This study investigated the effects of DEHP stress on the rhizosphere microenvironment of Brassica chinensis L. (Shanghai Qing) using a multi-omics approach. The results showed that soil dehydrogenase (S-DHA), soil urease (S-UE), and soil polyphenol oxidase (S-PPO) activities reached their maximum values at DEHP concentrations of 50, 20 and 20 mg/kg, respectively. S-DHA activity increased a dose-dependent manner, whereas S-UE index demonstrated a decreasing trend and S-PPO showed an increasing trend with increasing DEHP levels. The addition of DEHP significantly downregulated the contents of soil metabolites Trifolirhizin, Glycitin, Ganoderic acid D2, and Ceratodictyol, while Toddalolactone, Methylguanidine, Guanine, Calycanthine, Urea, and Hydrocortisone were significantly upregulated. As DEHP concentrations increased, both the Chao1 index and Shannon index decreased under stress treatment (2 mg/kg, 20 mg/kg, 50 mg/kg) compared with the control (0 mg/kg). DEHP altered soil bacteria community structure, reducing both diversity and abundance. Overall, this study provides insights into the complex interactions among DEHP, soil bacterial communities and soil metabolism, highlighting the need for targeted remediation strategies to mitigate DEHP-induced soil contamination.