Biomining / Bioleaching — Which bacteria are considered in biological leaching of sulfide ores and related operations?

Introduction / Context:Bioleaching exploits chemolithotrophic bacteria that oxidize reduced sulfur and ferrous iron in sulfide minerals, facilitating metal solubilization. The best-known genera historically include Thiobacillus (now Acidithiobacillus) and related iron-oxidizing bacteria used in heaps, dumps, and stirred bioreactors.

Given Data / Assumptions:

• Target metals are often associated with sulfide minerals (e.g., chalcopyrite, pyrite).
• Bacteria catalyze oxidation of Fe2+ to Fe3+ and reduced sulfur to sulfate, generating ferric iron and acid that attack the ore.
• Nomenclature has changed over time; older and newer names can refer to the same functional organisms.

Concept / Approach:Acidithiobacillus thiooxidans (formerly T. thiooxidans) oxidizes reduced sulfur; Acidithiobacillus ferrooxidans (formerly T. ferrooxidans) oxidizes Fe2+ and sulfur; and the historical designation Ferrobacillus ferrooxidans overlaps with iron-oxidizing bacteria considered in early bioleaching studies. All are part of the microbial consortium relevant to biomining.

Step-by-Step Solution:

Verification / Alternative check:Biomining case studies (e.g., copper heap leaching) repeatedly identify A. ferrooxidans and A. thiooxidans as dominant catalysts.

Why Other Options Are Wrong:

• E. coli K-12: a laboratory heterotroph with no role in sulfide bioleaching.

Common Pitfalls:Assuming name changes mean different organisms; taxonomy updates often rename well-known biomining species.

Final Answer:All of these