Effects of modified bentonites immobilized crude enzymes on soil properties and microbial community of BaP contaminated soil

Immobilized crude enzyme with sorption-modified bentonite presents a novel bioremediation strategy for recalcitrant polycyclic aromatic hydrocarbons (PAHs) in contaminated soils. However, the microbial community dynamics under PAH stressors remain unclear. Through a 30-day microcosm experiment using in situ contaminated soil, we systematically evaluated: (i) PAHs removal efficiency, (ii) dissolved organic matter (DOM) fractionation, and (iii) microbiome restructuring across three treatments: natural attenuation with contaminated soil (CK), saponin modified bentonite with contaminated soil (Sap-BT), and immobilized crude enzyme with modified bentonite with contaminated soil (CE-Sap-BT). The results showing that the addition of modified bentonites reached 52.45 % removal rate of Benzo[ a ]pyrene. Increased protein-like component (C1) and two humic-like components (C2 and C3) by 6.69 %, 12.57 % and 18.43 % compared to CK, while immobilized crude enzyme with sorption-modified bentonite enhanced the aerobic function of PAH-degrading microorganisms. Co-occurrence network analysis revealed the strong linkages of soil properties and key bacterial taxa. These results establish that immobilized crude enzyme with sorption-modified bentonite application coupling drives functional microbiome selection, providing novel insights into optimizing in situ PAH remediation protocols.