Bioremediation of environments contaminated with mercury. Present and perspectives

Mercury is a highly toxic heavy metal whose emission sources can be both natural and the result of anthropic activity. Its polluting action on soils, and its ability to spread through the atmosphere and aquatic environments, constitutes a threat to human and environmental health; both for its bioaccumulation capacity and for biomagnification through the trophic chain. For this reason, there is a growing scientific and social interest in the reduction of this heavy metal in ecosystems. Bioremediation based on the use of microorganisms and/or plants is postulated as a sustainable alternative to traditional physicochemical methods. The main strategies used for this purpose (individually or in combination) are the volatilization of the contaminant, biosorption, phytoextraction and phytoremediation. All these tools are based on taking advantage of the natural and evolutionary capacity that different organisms have developed to adapt to the presence of various pollutants in the environment. Based on the consulted bibliography, these bioremediation methodologies focus on the use of microorganisms (freely or associated with plants) have been successfully applied in different ecosystems, postulating themselves as a respectful alternative for the future for the recovery of degraded environments. For these reasons there is a growing interest in the scientific community to design and use new techniques in a “One Health” context, which allow interpreting the positive impact of bioremediation. In this sense, the universalization of Omics techniques has allowed to abound in the knowledge of new bacterial taxa, and their biotechnological application. This study pretends to cover the present knowledge about mercury bioremediation techniques. In the same way, some new techniques and perspectives are presented in order to expand the frontiers of future research.