A major organism used in commercial bioleaching for copper recovery is
1. Thiobacillusferrooxidans
2. Desulfovibriodesulfuricans
3. Pseudomonas aeruginosa
4. Aspergillusniger

Detailed Explanation:

The correct answer is: 1. Thiobacillus ferrooxidans

What is Bioleaching?

Bioleaching is a biotechnological process that involves the use of microorganisms to extract metals from their ores. It is widely used for low-grade ores that are not economically feasible to process using conventional methods.

This environmentally friendly approach is particularly important in copper mining, where microorganisms facilitate the solubilization of copper from its sulfide ores.

Role of Thiobacillus ferrooxidans:

Thiobacillus ferrooxidans (now reclassified as Acidithiobacillus ferrooxidans) is a chemoautotrophic bacterium that plays a key role in the bioleaching of copper. Here’s how it works:

• It oxidizes ferrous iron (Fe²⁺) to ferric iron (Fe³⁺).

• It also oxidizes sulfur compounds such as pyrite (FeS₂).

• Ferric iron acts as an oxidizing agent that helps solubilize copper from insoluble copper sulfide ores (e.g., chalcopyrite and covellite).

• This bacterium thrives in acidic environments, which is ideal for the bioleaching process.

Why Use T. ferrooxidans?

• It reduces environmental damage compared to traditional smelting.

• Cost-effective for processing low-grade ores.

• Can be used in heap leaching, a common industrial setup for large-scale metal recovery.

Other Options (Incorrect):

• Desulfovibrio desulfuricans – Known for sulfate reduction, not copper bioleaching.

• Pseudomonas aeruginosa – Involved in biodegradation, not specifically used for copper bioleaching.

• Aspergillus niger – A fungus used in bioleaching for other metals (e.g., zinc), not primarily copper.

Conclusion:

The major microorganism used in commercial bioleaching for copper recovery is Thiobacillus ferrooxidans. Its unique metabolic capabilities make it an essential tool in modern, sustainable mining practices, especially for low-grade copper ores.