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.

尽管此前已有针对亚马逊流域水体、土壤、沉积物及鱼类中汞（Mercury, Hg）污染状况的初步研究，但对于参与该元素微生物转化过程的微生物，尤其是哥伦比亚亚马逊地区的相关类群，目前仍知之甚少。因此，有必要对亚马逊生态系统中参与汞转化（还原与甲基化）的微生物群落开展评估，以期为理解该区域的汞污染问题提供基础认知、开发配套监测工具，并设计可助力生态修复的中长效生物修复策略。本研究旨在通过两种互补的差异化策略解析微生物群落多样性：其一，对受金矿开采不同程度干扰的水体、土壤及沉积物生态系统中的微生物群落进行普查；其二，分别开展基于merA基因（merA gene）介导的汞还原反应研究以筛选抗性菌株，以及基于hgcA基因（hgcA gene）的甲基化反应研究以评估其对亚马逊生态系统的影响——鉴于甲基汞是对生物体毒性最强的汞形态。