Monitoring bacterial community shifts in bioleaching of Ni–Cu sulfide

The microbial ecology of the bioleaching of Ni–Cu sulfide is poorly understood and little effort has been made to handle the microbiological components of these processes. In this study, denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA genes fragments from bacteria was used to evaluate the changes of the bacterial community in the process of Ni–Cu sulfide bioleaching in a shaken flask system. The results revealed that the bacterial community was disturbed after the addition of Ni–Cu sulfide. Phylogenetic analyses of 16S rRNA fragments revealed that the retrieved sequences clustered together with the genera Acidithiobacillus and Leptospirillum. Multidimensional scaling (MDS) and cluster analysis of DGGE-banding patterns revealed that the process of Ni–Cu sulfide bioleaching in 46 days was divided into three stages. During the bioleaching process of Ni–Cu sulfide, Leptospirillum was always dominant. The genera Acidithiobacillus was only detected at early and later stages of the bioleaching process. These results extend our knowledge on microbial dynamics in Ni–Cu sulfide bioleaching, a key issue required to improve commercial applications.