Title: Diversity analyses of microbial communities in Armanis gold-polymetallic mine and acid mine drainage: Bioremediation
Abstract:
Environmental pollution is among the most critical environmental concerns. Acid Mine Drainage (AMD) is considered to be one of the significant challenges that causes environmental damage worldwide. AMD is highly acidic and contains high levels of heavy metals, which threatens all living organisms: plants, animals and ultimately humans. In this study, modern molecular approaches (metagenomic) were used that allowed a more complete revealing the composition of microbial diversity in Armanis gold-polymetallic mine (Lori Region, Armenia). The microbial diversity of the acid mine drainage was investigated using culture-independent techniques, including Denaturing Gradient Gel Electrophoresis (DGGE) and high-throughput sequencing. A total of 103.493.310 and 112.789.352 bases were read. Data analysis identified 28 phyla, 63 classes, 129 orders, 264 families, and 738 genera. Proteobacteria were found to be the most abundant phylum in all the sampling sites, with the highest abundance (95%) in all samples, followed by Actinobacteria and Bacteroidetes. It was shown that AMD samples contained autotrophic iron oxidizing bacteria belonging to genera Leptospirillum, Acidithiobacillus, Sulfobacillus, as well as heterotrophic iron-reducing bacteria. Overall, classified and unclassified data verify that vast microbial biodiversity exists in AMD, much of which could not be identified with classical microbiology techniques. Besides, Cyanobacteria, a group of gram-negative bacteria that can obtain energy via oxigenic photosynthesis were also found in AMD samples. The most abundant blue-green algae were referred to genera Oscillatoria and Cyanobacteria. Blue-green algae can be used to treat AMD by removing toxic heavy metals (Cu, Zn, Pb, Hg) through a process called bioaccumulation, and by increasing the pH of the acidic water, which helps metals precipitate from the solution. Thus, the study of diversity and dissemination of microorganisms in ore deposits of Armenia, as well as their activity in AMD generation, is very important and relevant from the point of view of their dangerous effects on the environment. On the other hand, they can be beneficially used for bioremediation of AMD and other industrial wastes.
