Investigators from the Amazonian Institute of Scientific Research SINCHI identified two bacterial strains in mining sediments of the Colombian Amazon capable of withstanding extraordinary concentrations of mercury. This finding opens the possibility of applying bioremediation solutions to decontaminate rivers and wetlands affected by artisanal mining.
The bacteria belong to the genera Pseudomonas and Burkholderia contaminans, and naturally evolved in highly contaminated environments, developing genetic mechanisms that allow them to transform mercury into less toxic forms.
The mercury problem in the Amazon
Artisanal mining uses mercury to separate gold from sediments, leaving a deep footprint in rivers and forests.
When this metal reaches the water, it can convert into methylmercury, a compound that accumulates in fish and ascends the food chain, affecting both wildlife and indigenous and rural communities that depend on fishing.
The biological mechanism: mer operon
The resistance of these bacteria is based on a set of genes known as the mer operon, which acts as a molecular defense:
- Detects mercury in the environment.
- Activates proteins that capture it.
- Transforms it into a less toxic form that can be released into the atmosphere.
This process does not eliminate mercury globally, but it does reduce its concentration in sediments and waters, decreasing its availability to aquatic organisms.
Safety and potential use
The researchers analyzed the complete genomes of both strains and found:
- Low presence of genes associated with human diseases.
- Limited levels of antibiotic resistance.
This suggests a safer profile than other microorganisms used in similar projects, although any future application will require additional testing and regulatory evaluations.
Multiple metal resistance
Mining waste often contains mixtures of cadmium, lead, arsenic, copper, and zinc.
These bacteria also showed resistance to several of these metals, making them ideal candidates for real scenarios of multiple contamination.
Next steps
Pilot tests will need to verify:
- If they maintain their effectiveness outside controlled conditions.
- The speed at which they reduce mercury in real sediments.
- How they interact with existing microbial communities.
- Possible side effects on ecological balance.
The use of native bacteria offers advantages over invasive strategies by reducing the risks of introducing external species.
Expected impacts
If their effectiveness is confirmed, these bacteria could generate benefits on several levels:
- Less accumulation of mercury in fish and aquatic organisms.
- Progressive recovery of the ecological quality of rivers and wetlands.
- Reduction of risks for communities dependent on fishing.
- Improvement of biodiversity in degraded areas.
- Reduction of costs compared to conventional chemical treatments.
The discovery of mercury-resistant Amazonian bacteria represents a unique opportunity for environmental restoration in regions affected by mining.
With a safe genetic profile and multiple resistance capacity, these strains could become protagonists of a new generation of biological solutions to tackle contamination in the Amazon and other tropical ecosystems.
