Geomicrobiology of Mine Tailings from Malanjkhand Copper Project, India

Geomicrobiology of mine tailing from Asia's largest open-cast Cu mine at Malanjkhand was established, emphasizing the roles of microorganisms in acidification process using 16S rRNA gene amplicon and shotgun metagenomics. Mine tailings collected from five different locations portrayed the characteristic oligotrophic geochemical nature, with varying pH (pH 1.9-7.2), high heavy metals (Fe, Cu, Zn, Ni) and sulfate, but reduced, carbon, nitrogen and phosphate content. Iron-oxides and sulfate mineral phases were detected. Highly acidophilic, iron- and sulfur-oxidizing microorganisms includingSulfobacillus, Acidithiobacillus, Leptospirillium, Ferrimicrobium, Ferrithrix,etc. encoding the genes necessary for chemolithoautotrophic metabolism (sqr, sox, cbbL, cox, cyc1, etc.), resistance to low pH (sqh, kdp, gadB, etc.) and heavy metal stress (cop,cus,czc, chr,etc.) predominated the oxidized tailings. A markedly different microbial community represented byThiobacillus, Sphingomonas, Meiothermus, Sulfurifustis,and members ofHydrogenophilaceae, Acidiferrobacteraceae, Gaiellales, Gemmatimonadetes, Ignavibacteriales,KD4-96, etc. predominated the fresh tailings. Metagenome of the fresh tailings confirmed presence of similar sets of genes as found in oxidized tailings, however, taxonomic affiliations of most of these functional genes vary between the two habitats, indicating differential taxa recruitment under the two contrasting ecological conditions. The study provided an in-depth understanding of Cu mine tailings microbial community and their role in acidification process.

Automated summary

The study on the geomicrobiology of mine tailing from Asia's largest open-cast Cu mine at Malanjkhand revealed the presence of highly acidophilic iron- and sulfur-oxidizing microorganisms playing a crucial role in the acidification process. While the oxidized tailings were dominated by microorganisms such as Sulfobacillus and Acidithiobacillus, the fresh tailings showed a markedly different microbial community mainly consisting of Thiobacillus and Sphingomonas.