Bacteria help remove leftover plastic bags from lakes


Some bacteria in Europe’s lakes grow faster and more efficiently on plastic bag debris than on natural materials such as leaves and twigs, helping to eliminate plastic pollution in these ecosystems.

This follows from a study by seven researchers from institutions in Germany and the UK, published on Tuesday in the journal ‘Nature Communications’.

The work is based on 29 Scandinavian lakes analyzed between August and September 2019. These locations differed in latitude, depth, area, average surface temperature and diversity of dissolved carbon-based molecules.

The scientists cut up plastic bags from four UK chain stores and shook them in water until their carbon compounds were released.

At each lake, they filled glass bottles with water. They added a small amount of “plastic water” to half of them to represent the amount of carbon from plastics in the environment, and added the same amount of distilled water to the others. After 72 hours in the dark, they measured bacterial activity in each of the bottles.

Scientists point out that enriching waters with particular species of bacteria could be a natural way to remove plastic pollution from the environment.

Thus, they indicate that the rate of bacterial growth more than doubled when plastic pollution only increased the overall level of carbon in the lake water by 4%.


The results suggest that plastic pollution in lakes “primes” the bacteria for rapid growth because they not only break down plastic, but are also better able to break down other natural carbon compounds in the lake.

The study suggests that bacteria in the lake prefer plastic-derived carbon compounds to naturally occurring ones because carbon compounds in plastics are easier to break down and use as food.

Scientists warn that this does not justify today’s plastic pollution, as some of the compounds in plastics can have toxic effects on the environment, especially at high concentrations.

“It’s a bit like plastic pollution whetting the appetite of bacteria. Bacteria first use plastic as food because it is easy to break down, and then they are able to break down some of the most difficult foods: natural organic matter in the lake,” said Andrew Tanentzap from the University of Cambridge in Great Britain.

“This suggests that plastic pollution stimulates the entire food chain in lakes, as more bacteria means more food for larger organisms like ducks and fish,” he added.

The results will help prioritize lakes where pollution control is most urgent. If a lake has a lot of plastic pollution, but low bacterial diversity and many different natural organic compounds, then its ecosystem will be more vulnerable to plastic pollution.

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