In the streams of the Buenos Aires Metropolitan Area (AMBA), scientists from the University of Buenos Aires (UBA) and the Conicet discovered two native bacteria capable of breaking down highly persistent industrial dyes. The finding, published in Journal of Water & Health, shows that these bacteria can degrade up to 96.7% of Malachite Green and 87.6% of Acid Black 210 in less than 24 hours.
The breakthrough comes in a critical context: the watercourses of the AMBA are increasingly exposed to industrial discharges containing dyes that are difficult to remove, toxic to agriculture and marine environments.
The study and its methodology
The team led by doctors Alfredo Gallego and Sonia Korol took samples at five points in the AMBA: Río de la Plata, Medrano stream, Morón stream, La Boca, and Lanús.
- Water quality parameters, chemical and biochemical oxygen demand, and the presence of harmful bacteria were analyzed.
- Five dyes were selected: Malachite Green, Acid Black 210, Direct Orange 39, Alizarin Red, and Gentian Violet.
- The key test was to measure oxygen consumption: if it increased, the bacteria were degrading the compound.
In most sites, the dyes inhibited bacterial activity. However, the Medrano stream was the exception: there, the bacteria resisted and began to degrade the compounds, probably due to prolonged exposure to pollutants from nearby textile industries.
Main results
Of the 28 isolated bacteria, two strains stood out:
- Aeromonas sp., capable of degrading Malachite Green.
- Shewanella sp., efficient against Acid Black 210.
Both showed an efficiency greater than 87%, confirming that nature can offer solutions to persistent pollutants.
Environmental and social implications
The discovery opens the possibility of applying these bacteria in industrial effluent treatment plants, preventing dyes from reaching the streams. According to Gallego:
“The strains we identified could be used for effluent treatment and thus prevent further contamination of watercourses.”
Additionally, the researchers suggest that the presence of degrading bacteria can serve as a historical indicator of contamination in a stream. If they are not found, it could mean that the watercourse has not suffered prolonged exposure to dyes.
Next steps
The team continues to evaluate factors influencing degradation:
- Type of carbon source.
- Water pH.
- Temperature.
These studies aim to optimize the process’s efficiency and expand its application in different scenarios.
The Aeromonas sp. and Shewanella sp. bacteria discovered in the AMBA show that nature itself can help clean up what human activity pollutes. Their application in treatment systems opens the possibility of envisioning clearer rivers and streams, less toxic and with lower risk to public health.
