Effects of mercury contamination on microbial abundance and diversity in Amazon ecosystems disturbed by artisanal and small-scale gold mining

Despite initial studies in the Amazon to determine Hg contamination in water bodies, soils, sediments, and fish little is known about the microorganisms involved in the microbial transformations of this element, especially in the Colombian Amazon. Therefore, it is necessary to evaluate the microbial communities related to Hg transformations (reduction and methylation) in Amazonian ecosystems, in order to generate basic knowledge to understand the Hg problem in the region and create monitoring tools, as well as to design medium and long-term bioremediation strategies that contribute to its recovery. The aim of this paper was to evaluated the diversity of microbial communities, employing two different but complementary strategies: 1) to carry out an inventory of microbial communities in water, soil and sediment ecosystems with different degrees of intervention by gold mining and, 2) to study of Hg reduction mediated by the merA gene to search for resistant bacteria, and of methylation (hgcA gene) to evaluate its impact on Amazonian ecosystems, given that this is the most toxic form for living beings.