Potencial de biodegradação do imidacloprido por actinobactérias pertencentes aos gêneros Gordonia e Micrococcus

Abstract

Neonicotinoids comprise one of the most important groups of pesticides, with imidacloprid being one of the most widely used neonicotinoids. It is a contaminant that poses great risks to non-target organisms, such as pollinators. Bioremediation explores two processes that occur naturally in the environment, biodegradation and biotransformation. It consists of a biotechnological, economical, ecologically correct tool. In this context, the present study aims to verify the biodegradation capacity of the imidacloprid insecticide by strains of actinobacteria. The imidacloprid active ingredient was extracted from a commercial product to be used in biodegradation tests. Two strains were selected from the qualitative evaluation of the growth curve in control culture medium. Strains HEXBA05 and HEXBA06 showed shorter growth times and were used in imidacloprid biodegradation tests. The Gas Chromatography techniques coupled to Mass Spectrometry and Mass Spectrometry with Electrospray ionization by direct infusion were used in the analysis. Degradation metabolites were suggested based on standard spectra obtained by electron impact ionization available in the NIST 11 database and by comparison with sequential mass analysis (MS / MS) spectra. The metabolites nicotinic acid and 2-hydrazino-2-imidazoline have been suggested based on the comparison with standard fragmentation spectra obtained by electron impact with 94% and 87% similarity respectively. It was possible to verify the metabolic capacity of the strains for possible application in the bioremediation of the under study, since the metabolites 3-pyridinecarboxylic acid, 2-hydrazine-2-imidazoline, imidacloprid-urea and imidacloprid-guanidine were observed, which present less toxicity to insects and / or less environmental persistence than the precursor imidacloprid. Metabolites of equal toxicity or more toxic than the imidacloprid precursor such as, 5-hydroxy-imidacloprid, 6-chlorinicotinic acid and imidacloprid-olefin were not detected in the present study.