Effects of maize and peanut cultivation on microbial degradation of dibutyl phthalate in agricultural soil

Phthalate esters (PAEs) widely contaminate agricultural soils. Although microbes can degrade PAEs, how plants influence this process remains unclear. Using DNA-stable isotope probing and metagenomics, this study investigated the influence of plants on microbial degradation of PAEs by soil bacteria. Our results revealed that maize and peanut, representing non-legumes and legumes, exerted contrasting impacts on PAE microbial degradation. Specifically, peanut cultivation significantly enhanced PAE biodegradation efficiency by 26.53% compared to unplanted soil, whereas maize inhibited the process by 33.97%. Mechanism-driven analyses indicated that peanut facilitated PAE biodegradation by enriching active degraders and key degrading genes (e.g., pcaF, xylF, and benB-xylY) involved in biodegradation pathway II, recruiting Bacteroidetes, and alleviating nitrogen limitation (evidenced by increased abundances of nrfH, rhlA, and gspD). Furthermore, peanut cultivation promoted synergistic microbial interactions by increasing the diversity of taxa positively correlated with PAE degraders. In contrast, maize inhibited biodegradation by disrupting these processes and energy metabolism. This study sheds light on the plant-specific mechanisms driving PAE dissipation in soil.