Study on the life maintenance mechanism of Eisenia fetida under low-density polyethylene stress: Based on path analysis and canonical correlation analysis

The widespread use but low recovery rate of agricultural films has led to microplastic accumulation in farmlands, which poses a serious threat to the health of the soil ecosystem. There is an urgent need for early warning and monitoring of soil microplastics pollution, as well as the performance of bioremediation research. In this study, earthworms were used as test organisms to carry out toxicological tests under low-density polyethylene (LDPE) stress. A canonical correlation analysis model (CCA) was established to analyze the relationship between oxidative stress and microbial community. A path analysis model (PA) was also constructed to examine the detoxification mechanism of earthworms under LDPE stress. The results showed that low concentrations (100 and 500 mg/kg) of LDPE did not cause oxidative damage to earthworms but stimulated their physiological metabolism. Meanwhile, 1000 mg/kg LDPE concentrations caused oxidative damage to earthworms and altered their internal microbial community structure. Furthermore, at 1500 mg/kg LDPE concentrations, the oxidative stress to the earthworms is aggravated, and their physiological responses work in conjunction with the microbial community to cope with the adverse condition. Lastly, treatment with 2000 mg/kg LDPE induced the appearance of LDPE tolerant populations in the microbial community in vivo. Taken together, our results provide a theoretical basis for revealing the physiological response of earthworms when challenged in a polluted environment and provide a model for pollution remediation and ecological security monitoring of soil ecosystems.