Hongbo Zhao - Biohydrometallurgy of Chalcopyrite

Bioleaching systems are a type of extremely acidic environment known to be harmful to most prokaryotes and eukaryotes. There is a wide biodiversity of acidophilic microorganisms in these eco-environments. Many studies have investigated acidophilic prokaryotes related to industrial bioleaching, primarily because of their potential for commercial application. Metagenomics allows us to acquire potential resources from both cultivatable and uncultivable microorganisms in the environment. Here, shotgun metagenome sequencing was used to investigate microbial communities from the surface layer of low-grade copper tailings that were industrially bioleached at the Dexing Copper Mine, China. A bioinformatics analysis was further performed to elucidate structural and functional properties of the microbial communities in a copper bioleaching heap. Taxonomic analysis revealed unexpectedly high microbial biodiversity of this extremely acidic environment, because most sequences were phylogenetically assigned to Proteobacteria, whereas there was a low proportion of Euryarchaeota -related sequences in this system, assuming that Archaea probably had little role in the bioleaching systems. At the genus level, the microbial community in the mineral surface-layer was dominated by sulfur- and iron-oxidizing acidophiles such as Acidithiobacillus -like populations, most of which were Acidithiobacillus ferrivorans -like and Acidithiobacillus ferrooxidans -like groups. In addition, Caudovirales were the dominant viral type observed in this extreme environment. Functional analysis illustrated that the principal participants related to key metabolic pathways (carbon fixation, nitrogen metabolism, Fe(II) oxidation, and sulfur metabolism) were mainly identified to be Acidithiobacillus -like, Thiobacillus -like, and Leptospirillum -like microorganisms, indicating their vital roles. Our study provides several valuable datasets for understanding the composition and function of the microbial community in the surface layer of the copper bioleaching heap.