Biodegradation Pathway of the Pyrethroid Pesticide Esfenvalerate by Bacteria from Different Biomes

摘要

This manuscript reports on a study of new biocatalysts for the biodegradation of pyrethroid pesticides, such as esfenvalerate. Experiments of esfenvalerate biodegradation by bacteria isolated from Brazilian savannah (Curtobacterium sp. CBMAI 1834, Bacillus sp. 2B, Lysinibacillus sp. CBMAI 1837, and Bacillus sp. 4T), sea (Kocuria sp. CBMAI 135, Kocuria sp. CBMAI 136, Kocuria marina CBMAI 141, and Kocuria sp. CBMAI 145), and a tropical peat usually known as "turfa" soil (Bacillus sp. P5CBNB, Kosakonia sp. CBMAI 1836, Bacillus sp. CBMAI1833, and Kosakonia sp. CBMAI1835) were performed. A biodegradation pathway was proposed for a better understanding of the environmental fate of the above mentioned insecticide. Esfenvalerate (S,S-fenvalerate) and its metabolites [3-phenoxybenzaldehyde (PBAld), 3-phenoxybenzoic acid (PBAc), 3-phenoxybenzyl alcohol, and 2-(4-chlorophenyl)-3methylbutyric acid) (CLAc)] were quantitatively analyzed in triplicate experiments by a validated method. Initially, 100 mg L-1 esfenvalerate (Sumidan 150SC) was added for each experiment. The residual esfenvalerate (104.7-41.6 mg L-1) and formation of PBAc (0.1-8.1 mg L-1), ClAc (1.5-11.0 mg L-1), PBAlc (0.9mg L-1), and PBAld (completely biotransformed) were quantified. The 12 bacterial strains accelerated (with different efficiencies) the esfenvalerate degradation and increased the metabolites concentrations. A new and more complete biodegradation pathway based on HPLC-time of flight (ToF) and gas chromatography-mass spectrometry (GC-MS) analyses (in which thermal instability products were detected) was proposed. The detected metabolites are smaller and more polar compounds thatmaybe carried by water and contaminate the environment.