In 2019 a study by the University of Newcastle, Australia, showed us that, on average, we ingest 5 grams of plastic per week, the equivalent of a credit card.
A contamination caused by microplastics — plastic particles smaller than 5 mm — that is appearing in food, drinking water and even the air we breathe. According to the study, people around the world ingest an average of 2.000 microplastics per week.
These particles come from multiple sources: artificial fibers in our clothing, microspheres in toothpaste or larger pieces of plastic that gradually degrade after being thrown away and ending up entering rivers and oceans.
Although they are tiny, the risk they pose to the environment is enormous. Microplastics are not easily biodegradable and the current techniques employed to eliminate them, such as filters, are not 100% effective or imply the use of aggressive chemicals, not preventing microplastics from entering the natural environment, and putting marine life and humans at risk: microplastics have been found in the liquids we drink and even in the salt we season food with.
Now a team of microbiologists from Hong Kong Polytechnic University has created a bacterial biofilm capable of capturing these small particles.
Bacteria tend to group together to adhere to surfaces, creating an adhesive substance, a kind of film called biofilm (a common example is the bacterial plaque on teeth, formed by the accumulation of bacteria present in the mouth).
The research, still in its embryonic stage, shows promising results as a sustainable solution to treat the scourge of microplastics. The team’s discovery came from the bacterium Pseudomonas aeruginosa*, which originates a biofilm that works as a sticky tape bioaggregating the harmful microplastics that float in the water.
These microbe nets capture the microplastics, causing them to sink in the water. Then, thanks to an inducible dispersion mechanism, researchers manage to release the microplastics from the biofilm and gather them to be recycled.
On a large scale, this natural system could prevent the plastic particles from contaminating aquatic ecosystems when applied, for example, in wastewater treatment plants.
Schematic illustration of the ‘capture-and-release’ mechanism engineered by P. aeruginosa:
* The tests were carried out in a controlled laboratory environment since Pseudomonas aeruginosa is a transmitter of diseases to humans and may not be used in the most adequate bacterium for large-scale tests/projects. The researchers are confident that the method can work using other bacteria with similar behavior.