Seleção de Enterococcus sp. resistente a cobre e a mercúrio com potencial aplicação na biorremediação

Abstract

The presence of heavy metals can occur naturally or as a consequence of anthropogenic activities. Mercury is one of the most toxic elements, since copper is an essential micronutrient for all living things, but in large concentrations can cause serious environmental problems. Thus, high concentrations of metals in the environment lead to bacterial species becoming resistant by the presence of resistance genes. Considering this scenario, the objective of this work was to verify the resistance to heavy metals in Enterococcus sp. This study included 72 isolates from water, soil and sediment. Resistance screening was applied by the gradient plate technique, containing increasing concentrations of copper ion. Subsequently, the isolates were tested on a microdilution plate containing 0.018, 0.009 and 0.0045 mg/L of the metal. The presence of genes that confer resistance to copper (tcrB) and mercury (merA) was verified by the Polymerase Chain Reaction (PCR) technique. The results revealed that 100% of the isolates were resistant to all concentrations of copper analyzed. The tcrB gene was present in 44% of the isolates. The merA gene was not detected. Considering the lack of research of this nature in Brazil, this study generates information that may contribute to the use of these bacteria for the decontamination of heavy metals in a given area.