Flonicamid is a novel, selective, systemic pyridinecarboxamide insecticide that effectively controls hemipterous pests. Sulfoxaflor, a sulfoximine insecticide, effectively controls many sap-feeding insect pests. Ensifer meliloti CGMCC 7333 transforms flonicamid into N-(4-trifluoromethylnicotinoyl) glycinamide (TFNG-AM). Resting cells of E. meliloti CGMCC 7333 (optical density at 600 nm [OD600] = 5) transformed 67.20% of the flonicamid in a 200-mg/L solution within 96 h. E. meliloti CGMCC 7333 transforms sulfoxaflor into N-(methyl(oxido){1-[6-(trifluoromethyl) pyridin-3-yl] ethyl}-k4-sulfanylidene) urea (X11719474). E. meliloti CGMCC 7333 resting cells (OD600 = 5) transformed 89.36% of the sulfoxaflor in a 200 mg/L solution within 96 h. On inoculating 2 mL of E. meliloti CGMCC 7333 (OD600 = 10) into soil containing 80 mg/kg flonicamid, 91.1% of the flonicamid was transformed within 9 d (half-life 2.6 d). On inoculating 2 mL of E. meliloti CGMCC 7333 (OD600 = 10) into soil containing 80 mg/kg sulfoxaflor, 83.9% of the sulfoxaflor was transformed within 9 d (half-life 3.4 d). Recombinant Escherichia coli harboring the E. meliloti CGMCC 7333 nitrile hydratase (NHase)-encoding gene and NHase both showed the ability to transform flonicamid or sulfoxaflor into their corresponding amides, TFNG-AM and X11719474, respectively. These findings may help develop a bioremediation agent for the elimination of flonicamid and sulfoxaflor contamination.
Keywords: Ensifer meliloti CGMCC 7333; Flonicamid; biotransformation; nitrile hydratase; sulfoxaflor.