Microbial network stability in chlorpyrifos-contaminated soils is improved by microbial inoculant application

Abstract

Soil degradation caused by organophosphorus pesticide (OPP) residues poses a critical environmental challenge. However, the remediation efficiency of microbial inoculants, as well as the underlying mechanisms, in OPP-contaminated soils remain unclear. In this study, microcosm-controlled experiments combined with high-throughput sequencing were performed to systematically investigate the remediation efficiency of microbial inoculants, as well as the underlying mechanisms, in OPP-contaminated soils. Compared with the chlorpyrifos-exclusively treatment (CPF), the chlorpyrifos plus microbial inoculant treatment (MI) significantly increased the soil organic carbon (SOC), total nitrogen (TN), and available phosphorus (AP) contents (p < 0.05) while markedly increasing the β-glucosidase (BG) and catalase (CAT) activities by up to 202.8 % and 30.9 %, respectively. Notably, with prolonged incubation, the AP and available potassium (AK) contents decreased in CPF treatment, whereas they increased under the MI treatment. The MI treatment restructured the microbial community composition by enriching copiotrophic microorganisms (Proteobacteria) while suppressing oligotrophic microorganisms (Acidobacteria). Network analysis revealed that the MI treatment improved the modularity and robustness of soil microbial networks. Mechanistically, MI treatment enhanced the stability of microbial communities to environmental disturbances by mediating nutrient-regulated soil enzyme activities. Random forest modeling identified SOC and BG as pivotal regulators of microbial network stability. This study confirms the theory of synergistic adaptation between microbial network complexity and stability, providing a scientific basis to optimize soil bioremediation technologies for sustainable agriculture.