Long-term co-exposure to phthalates and cadmium enhances the stability of soil microbial communities

A three-year microecological experiment was conducted using industrially polluted soil treated with varying concentrations of Cd(II) and agricultural films containing Phthalate esters (PAEs). A microecological cultivation experiment was conducted using soil samples collected from an industrially polluted area. Results showed that Co-exposure to Cd(II) and PAEs significantly altered the soil microbial community structure and diversity. The total PAEs content in the soil decreased in the presence of Cd(II), while the proportion of residual Cd(II) increased. The co-existence of Cd(II) and PAEs enhanced the mobility of both pollutants and increased the abundance of certain microbial taxa, such as Pseudomonadota and Acidobacteriota, while decreasing the abundance of Nocardioides, Sphingomonas, and Streptomyces. The enhanced bioavailability of Cd(II) and PAEs has a greater impact on the structure of fungal communities than on bacterial communities. The Mantel analysis results indicated that BBP content had the most significant influence on the bacterial and fungal communities. Co-occurrence network analysis revealed that combined exposure to Cd(II) and PAEs increased the complexity and stability of the microbial community network. The degradation pathway of Aminobenzoate was upregulated under co-exposure conditions, while Nitrotoluene and Steroid degradation pathways were significantly downregulated. The observed enrichment of Pseudomonadota and Acidobacteriota, coupled with the upregulation of the Aminobenzoate degradation pathway, suggests these taxa and metabolic functions may play crucial roles in the co-degradation of PAEs under Cd(II) stress. Furthermore, the increased network complexity and stability indicate a potential adaptive microbial response to combined pollution. These insights point towards the potential for harnessing these specific microbial consortia and functional pathways for the targeted bioremediation of co-contaminated sites.