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Fipronil is a broad-spectrum insecticide with remarkable efficacy that is widely used to control insect pests around the world. However, its extensive use has led to increasing soil and water contamination. This fact is of concern and makes it necessary to evaluate the risk of undesirable effects on non-target microorganisms, such as the microbial community in water and/or soil. Studies using the metagenomic approach to assess the effects of fipronil on soil microbial communities are scarce. In this context, the present study was conducted to identify microorganisms that can biodegrade fipronil and that could be of great environmental interest. For this purpose, the targeted metabarcoding approach was performed in soil microcosms under two environmental conditions: fipronil exposure and control (without fipronil). After a 35-day soil microcosm period, the 16S ribosomal RNA (rRNA) gene of all samples was sequenced using the ion torrent personal genome machine (PGM) platform. Our study showed the presence of Proteobacteria, Actinobacteria, and Firmicutes in all of the samples; however, the presence of fipronil in the soil samples resulted in a significant increase in the concentration of bacteria from these phyla. The statistical results indicate that some bacterial genera benefited from soil exposure to fipronil, as in the case of bacteria from the genus Thalassobacillus, while others were affected, as in the case of bacteria from the genus Streptomyces. Overall, the results of this study provide a potential contribution of fipronil-degrading bacteria. [ABSTRACT FROM AUTHOR]

BACKGROUND Fipronil is a broad‐spectrum insecticide that is used extensively due to its effective action in pest control. However, environmental studies have shown it has high toxicity towards non‐target organisms as well. In addition, the degradation of fipronil can generate even more toxic and reactive metabolites in the environment. In the present study, bioprospecting for bacteria with the potential to degrade fipronil was performed using fipronil as the sole source of nitrogen and main source of carbon. From samples of corn culture soil with a history of fipronil application, isolation was performed using the microcosm enrichment method. RESULTS: Bacteria were isolated using fipronil (0.6 g L−1) as the sole nitrogen source and main carbon source. After preliminary tests, isolate E1 was selected and, following sequencing of 16S rRNA, it was found that the isolate E1 was a bacterium of the Bacillaceae family, Bacillus megaterium species. Growth was evaluated by dry biomass and degradation quantified by gas chromatography–mass spectrometry (GC–MS). Strain E1 presented a 94% degradation of fipronil, as well as 91% and 96% degradation of its metabolites fipronil‐sulfide and fipronil‐sulfone, respectively, in 14 days, reducing its initial concentration from 0.6 g L−1 to 0.036 mg L−1. CONCLUSION: The results showed that bioprospecting of the E1 strain, isolated from soil, showed efficiency in the biodegradation process of fipronil. This strain is a potential candidate for use in bioremediation processes in areas contaminated with fipronil and for use in further studies on the elucidation of the metabolic pathways of fipronil degradation. © 2021 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]