Mechanisms of cypermethrin degradation and remediation by Rhodococcus sp. H-3: Insights from comparative genomics, hydrolase CymE1 secretory expression, and bacterial community analysis
Cypermethrin, a common pyrethroid insecticide, raises significant ecological concerns due to its widespread use. In this study, a highly efficient cypermethrin-degrading strain, Rhodococcus sp. H-3, was isolated. The strain was capable of degrading 30 mg/L cypermethrin at the rate of 83.48 % within 7 days and it could hydrolyze cypermethrin into 3-phenoxybenzoic acid (3-PBA) and permethric acid (DCVA). A novel cypermethrin degradation gene, cymE1 , was identified in strain H-3 through genome analysis, and its highest level of amino acid sequence similarity observed was 33.50 % in the Swiss-Prot database. The functional strain, SCK6-E, which could secrete CymE1, was successfully constructed by using double-exchange strategies. Strain SCK6-E could be applied for the removal of cypermethrin residues from tea plant leaves with a removal rate of 57.83 % within 2 h. Furthermore, strain H-3 demonstrated the capability to remediate cypermethrin-contaminated soil, exhibiting a degradation rate of 65.80 % over 10 days. The results of the 16S rRNA high-throughput sequencing indicated that strain H-3 was conducive to the restoration of the diversity and richness of the bacterial community in the soil. This study provides novel strain and gene resources for researching the degradation mechanism of pyrethroids, and offers valuable insights for developing effective pesticide residue remediation strategies.
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