Abstract
Background: Acid mine drainage (AMD) is a worldwide environmental menace with its multifaceted extreme nature, yet, it harbors diverse microorganisms with novel lineages and provides new insights into evolution, adaptation and metabolism. With tight coupling between biological and geochemical processes, AMD microbes play crucial roles in biogeochemical cycles and in constant focus for microbial ecology research through quantitative, genome and metagenome based analysis. This study on microbiome of AMD from Malanjkhand copper mine sheds new light of the general assumptions on microbiome emphasizing the roles of local geochemistry in community assemblages and functions using the samples from an unexplored mine.Results: Malanjkhand AMD samples showed a regime of acidic pH with elevated levels of iron, sulfate and heavy metals. 16S rRNA gene amplicon and metagenome sequencing revealed that environmental pH controlled the species abundance, richness and assemblages. Extreme acidic niches were predominated by chemolithotrophic iron- and sulphur- oxidizing taxa (Leptospirillium, Acidithiobacillus, Ferrithrix, Ferrimicrobium, and Metallibacterium) capable of pyrite dissolution. In contrast, the moderately acidic niches were flourished with heterotrophic populations (Sphingomonas, Nitrosomonas, Gemmatimonas, Meiothermus, Novosphingobium, Polaromonas, Desulfurispora, Desulfomonile) involved in diverse carbon and nitrogen metabolism, sulfate and metal reduction. Relative abundance of taxa, co-occurrence, ANOSIM, and PERMANOVA revealed strength of the selective pressure in habitat-specific microbial guilds. Results indicated that individual species’ ability to withstand and flourish under the extreme low pH environment was an important driver for community association, while metabolic interdependencies could be the major factor controlling species interaction within relatively higher pH habitats. Gene abundance in the metagenomes suggested that sulfur/iron oxidizing, carbon fixing, denitrifying, and stress tolerant microbial populations were predominated in both the samples. Metagenome analysis further revealed that only a small set of sulfate/metal reducing populations was abundant in higher pH samples, indicating their potential in natural attenuation of AMD.Conclusion: Our study provided a deeper understanding about the composition and function of microbial communities within AMD highlighting the roles of local geochemistry in regulating species abundance, distribution, and interrelations. Genomic potential of AMD microbiome in withstanding the extremities and role in biogeochemical cycles, affecting metabolism as well as fate of major hazardous constituents was elucidated.
Jarosite versus Soluble Iron-Sulfate Formation and Their Role in Acid Mine Drainage Formation at the Pan de Azúcar Mine Tailings (Zn-Pb-Ag), NW Argentina
