Monitoring of a pyrite-oxidising bacterial population using DNA single-strand conformation polymorphism and...

Area of Science:

• Microbial Ecology
• Biotechnology
• Geochemistry

Background:

• Bacterial consortia play a crucial role in bioleaching processes, particularly in the oxidation of metal sulfides like cobaltiferous pyrite.
• Understanding microbial community dynamics is essential for optimizing bio-reactor efficiency in mining and environmental remediation.

Purpose of the Study:

• To investigate the evolution of bacterial consortia during batch oxidation of cobaltiferous pyrite.
• To compare microbial community structure and dynamics in a bubble column versus a stirred tank bio-reactor.
• To determine the distribution of bacteria between solid-associated and planktonic phases.

Main Methods:

• Single-strand conformation polymorphism (SSCP) technique for analyzing bacterial community structure.
• 16S rDNA sequencing for precise identification of bacterial species.
• Polymerase Chain Reaction (PCR) combined with SSCP for quantitative analysis.
• Microscopic techniques for assessing bacterial distribution (solid-associated vs. planktonic).

Main Results:

• Three dominant bacterial phylotypes were identified: Leptospirillum ferrooxidans, Acidithiobacillus thiooxidans, and Sulfobacillus thermosulfidooxidans.
• Acidithiobacillus thiooxidans-related bacteria were initially dominant in the liquid phase but were later replaced by Leptospirillum ferrooxidans-related bacteria.
• Leptospirillum ferrooxidans-related bacteria consistently predominated in the solid-associated fraction.
• Sulfobacillus thermosulfidooxidans-related bacteria showed enhanced growth in the bubble column bio-reactor.

Conclusions:

• Bacterial community composition and distribution are significantly influenced by bio-reactor type and the phase of bioleaching.
• Leptospirillum ferrooxidans is better adapted to solid-associated growth, while Acidithiobacillus thiooxidans dominates the planktonic phase in early stages.
• Bubble column reactors may offer advantages for the growth of specific thermophilic bacteria like Sulfobacillus thermosulfidooxidans in pyrite bioleaching.