DEGRADATION OF CYPERMETHRIN BY PSYCHROBACTER SP. AB2 ISOLATED FROM CYPERMETHRIN-TREATED AGRICULTURAL SOILS IN LAGOS, NIGERIA

Abstract

The ecological safety and health risk of cypermethrin is an emerging concern due to its carcinogenic, neurotoxic, and endocrine-disrupting effects on non-target organisms. The specific objective of this study was to isolate and characterize bacterial strains from cypermethrin-treated agricultural soils that are able to utilize cypermethrin as the sole source of carbon and energy. Psychrobacter faecalis strain AB2 was isolated using the aerobic enrichment culture technique. Degradation of cypermethrin and release of 3-Phenoxybenzoic acid (3-PBA) were detected using gas chromatography (GC) and reversed-phase high-performance liquid chromatography (HPLC). HPLC measurements of the culture supernatants showed that hydrolytic cleavage of the ester bond in the cypermethrin molecule resulted in the release of 3-PBA up to the level of 15.4 % by strain AB2 during growth on MSM supplemented with cypermethrin. Based on the result of 16S rRNA gene sequencing, the isolated bacterial strain was identified as Psychrobacter faecalis strain AB2 (KF688134). Strain AB2 exhibited a growth rate of 0.025 h^-1 and a doubling time of 27.79 h^-1 during growth in MSM supplemented with cypermethrin. Microcosm experiments showed the percentage of cypermethrin degradation was 60.19 % by strain AB2 after 20 days of incubation. Strain AB2 utilized a range of aromatic compounds as carbon sources, indicating its potential for bioremediation of a polluted environment.