Metagenomic analysis of microbial psychrotolerant consortia leaching of metal sulfides at low temperatures.

The bioleaching processes are limited by the availability of O2 and low temperatures (3°C to 15°C) in Andean mining zones. These parameters limit bacterial leaching operations because decrease the rate of iron oxidation by mesophilic microorganisms. This study aimed to isolate and characterize microbial psychrotolerant consortia leaching (MPCL) that can be used in industrial processes for metal recovery units at high altitude mining operation. We collected and cultured 11 samples of acidic water from the Volcan mining company (4261 m.a.s.l) located in the city of Cerro de Pasco, the Huarón mine (4534 m.a.s.l) located in the district of Huayllay, and Yanamate Lake (4358 m.a.s.l) located at the southeast of Cerro de Pasco city. We obtained 6 MPCL that oxidized copper sulfide 0.5%(w/v) and zinc sulfide 0.5%(w/v) at 5ºC. Growth kinetics of the 6 MPCL were evaluated and doubling times of 49.5 hours for CuS and 60.8 hours for ZnS were obtained. The release of copper kinetics on a sulphide ore and synthetic sulphide (CuS) were evaluated, obtaining better results in CuS, where copper (II) was released to 1.51 mg/L for every 10^5 cells/ml. Metagenomic DNA of the 6 consortia were extracted. The amplicons libraries were built and sequenced using 27F and 518R primers. The consortia were mostly composed for the genus Acidithiobacillus sp. and only in one of them Leptospirillum ferroxidans was present.