Biohydrometallurgy — key microbe in copper bioleaching Which microorganism is the principal industrial agent used in commercial bioleaching operations for copper recovery from low-grade ores and concentrates?

Introduction / Context:
Bioleaching exploits chemolithotrophic microbes to catalyze the oxidation of ferrous iron and reduced sulfur minerals, accelerating metal solubilization. Copper heap and dump leaching rely on a small set of acidophilic bacteria adapted to low pH and high metal loads.

Given Data / Assumptions:

• Target metal: copper from sulfide ores (for example, chalcopyrite, chalcocite).
• Process conditions: acidic, aerated, often elevated ferric/ferrous cycling.
• The classical organism name Thiobacillus ferrooxidans is widely known; modern taxonomy places it as Acidithiobacillus ferrooxidans.

Concept / Approach:
Acidithiobacillus ferrooxidans oxidizes Fe2+ to Fe3+ and reduced sulfur to sulfate, generating ferric iron and acid that chemically attack sulfide minerals, liberating copper. Although consortia including Leptospirillum and A. thiooxidans contribute, A. ferrooxidans is the canonical bioleaching species highlighted in industrial practice.

Step-by-Step Solution:
Identify the organism most associated with copper bioleaching.Associate its metabolism (iron and sulfur oxidation) with metal solubilization.Select Thiobacillus (Acidithiobacillus) ferrooxidans.

Verification / Alternative check:
Mining biotechnology texts and operating heap-leach case studies consistently cite A. ferrooxidans as a core bioleaching agent.

Why Other Options Are Wrong:
Desulfovibrio desulfuricans is sulfate-reducing (anaerobic) and used in bioremediation, not oxidative leaching; Pseudomonas aeruginosa is not a principal leaching microbe; A. niger can bioleach via organic acids but is not the main copper heap organism; Leptospirillum interrogans is a misapplied species name (Leptospirillum ferrooxidans is relevant, but the classic answer is A. ferrooxidans).

Common Pitfalls:
Confusing acidophilic oxidizers with sulfate reducers; conflating fungal organic-acid leaching with chemolithotrophic sulfide oxidation.

Final Answer:
Thiobacillus ferrooxidans (Acidithiobacillus ferrooxidans).