Geomicrobiology of Mine Tailings from Malanjkhand Copper Project, India

Abstract

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 including Sulfobacillus, 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 by Thiobacillus, Sphingomonas, Meiothermus, Sulfurifustis, and members of Hydrogenophilaceae, 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.

Keywords:

• Acidification
• biogeochemical cycling
• iron- and sulfur-oxidation
• microbial diversity
• mine tailings
• metagenomics

Acknowledgments

The generous help from Malanjkhand Copper Project, Hindustan copper limited authority for sample collections is acknowledged.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Authors are thankful to Department of Biotechnology, Government of India for funding the project [BT/PR 7533/BCE/8/959/2013, Dated 10/12/2013]. The next generation sequencing facility used in this work was created by PS through IIT Kharagpur SGBSI challenge grant [IIT/SRIC/BT/ODM/2015-16/141]. AG thanks the Department of Biotechnology, Government of India for providing fellowship under DBT-JRF category [DBT/2014/IITKH/113]. AD thanks Indian Institute of Technology Kharagpur for his fellowship.