Monitoramento e isolamento microbiano a partir de sistema de biorremediação de pesticidas

Abstract

The accumulation of pesticide residues from agricultural activities causes contaminations in soil, groundwater and along the food chain. One way to minimize the pollution caused by these substances is the bioremediation technique, which can be applied in biobed systems. To biologically monitor pesticide degradation, the efficiency of the system was evaluated through the microbial dynamics against different compositions of pesticides discarded in the biobed installed at UTFPR's experimental farm in Dois Vizinhos and bacteria capable of growing in high concentrations of glyphosate, which are potential degraders of this compound, were bioprospected. To monitor the microbial dynamics, every 15 days, two soil samples were collected at different depths of the biobedding (20 and 40 cm). For 4 months, these samples were prepared and submitted to the colony extraction and counting process, and the results were represented in CFU.mL-1. In a survey previously carried out, it was found that the main herbicide used on the UTFPR experimental farm is glyphosate. Because of this, the bioprospecting of cultivable bacteria in the presence of glyphosate was preceded by an enrichment process with successive additions of glyphosate to the culture with mineral salts medium (MSM), and characterized by the Gram staining technique. As a result, two gram-negative bacteria that grew in the presence of 7.2 mg.mL-1 of glyphosate were isolated. Finally, based on the analyses, it was possible to verify a wide variety of microorganisms present in the biobed, as well as to bioprospect bacteria that can be cultivated in the presence of glyphosate.