A new strategy for removing insecticide etoxazole from soil using a combination of a novel Paracoccus versutus Y4 and a fungal mycelium carrier

Etoxazole is a widely used insecticide that poses a serious threat to both ecosystems and human health. In present study, a novel strain Paracoccus versutus Y4 was isolated and identified. More than 98 % of the etoxazole (10 mg/L) was degraded as the sole carbon source within 8 d by strain Y4 in liquid culture. HPLC MS/MS analysis revealed three possible intermediates, and a novel metabolic pathway of etoxazole including oxidation, dehydrogenation, and hydrolysis reactions was proposed. The Toxicity Estimation Software Tool suggests that the biodegradation intermediates were less harmful than etoxazole. Whole-genome sequencing revealed that the genome size of P. versutus Y4 was 5320,902 bp containing 5187 coding sequences. Among them, the gene coding monooxygenase, dehydrogenase and hydrolase may be responsible for etoxazole biodegradation. The results of molecular docking analysis suggested that the monooxygenase, dehydrogenase, and hydrolase from strain Y4 may facilitate catalytic degradation through efficient substrate binding. Compared with diatomite carrier, fungal mycelium carrier can promote the growth of strain Y4. In the soil degradation experiments, the fungal mycelium carrier promoted etoxazole degradation by strain Y4 in both fresh and sterilized soil. Treatment with Y4 +fungal mycelium significantly reduced the half-life of etoxazole in fresh soil from 24.2 to 6.3 d. Our study is the first to isolate etoxazole-degrading bacteria and provides a new strategy for the bioremediation of pesticide pollution by combining degrading microbes and fungal mycelium carriers.