SHORT COMMUNICATION: EVOLUTION OF BACTERIAL COMMUNITY IN A PYRITIC REFRACTORY GOLD ORE COLUMN LEACHING ENVIRONMENT

This short communication highlights important biological features of a pyritic refractory gold ore heap-leaching environment. Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans were to be two of only three bacterial species detected on the ore surfaces at ambient temperature. Sulfobacillus was not originally introduced in the inoculum, but was later detected in the column. Only organisms of the Leptospirillum genus were present in the ferric sulfate leaching solution. Ignoring that the ore hosted approximately 500 times more microorganisms than the solution can greatly underestimate the oxidizing potential. One or more of these microorganisms oxidized ferrous ions, leading to a rise in the solution potential. They also oxidized elemental sulfur, resulting in a higher sulfate yield than measured in sterile medium.