Bacterial Community Changes with Depth and Metal Geochemistry in Spent Ore Gold Heap Leach

摘要

Bacterial communities from a spent ore gold heap leach facility were characterized using SSU rRNA gene pyrosequencing to assess population distributions and potential impacts for in situ biomining. Methods for nucleic acid extraction from spent rock were optimized and the sequences were assessed with various quality controls, e.g., sub-sampling to reduce over-estimation of species richness as well as comparison of adaptor-ligation or fusion primer prepared samples. Predominant microbial populations at certain sampling depths included Proteobacteria-like sequences. Multiple populations could be classified into 'functional groups', e.g., organic acid production, metal-oxidation, sulfur-oxidation, and cyanide production/degradation, which are all biogeochemical processes relevant to biomining. These results demonstrated that bacterial communities could be assessed via pyrosequencing and that microbial community structure was impacted by sample depth and metal levels. A better understanding of the interactions between microbes and the local environment will allow improved design of in situ engineering configurations that stimulate microbial activities for more efficient metal recovery and subsequent site maintenance.