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A research study involving 29 European lakes found that some naturally occurring freshwater bacteria grow faster and more efficiently on leftover plastic bags than on plant matter such as leaves and twigs. The scientists behind the research believe that enriching bodies of water with these types of bacteria could be a way to remove plastic pollution from the environment.
The results of the study, published in Nature Communications, suggest that plastic pollution in lakes “primes” bacteria for rapid growth. Not only do the bacteria break down plastic, but they are better able to break down other natural carbon compounds in the lake. Scientists believe this happens because the carbon compounds in the plastics break down more easily as food for bacteria.
“It’s almost as if plastic pollution gives the bacteria an appetite.” “The bacteria first use the plastic as food because it breaks down easily, and then they are able to break down some of the more difficult food – the natural organic matter in the lake,” said Andrew Tanentzap, one of the collaborators. – the authors of the study, in a press release. Tanentzap is part of the University of Cambridge’s Department of Plant Sciences. A study by the same authors published last year found European lakes to be potential hotbeds of microplastic pollution.
As plastics break down over the years, they release simple carbon compounds. These compounds are different from those released by organic matter such as leaves and twigs. Carbon compounds released by plastics have been shown to come from additives added to plastic products, including adhesives and plasticizers.
For this study, the researchers sampled 29 lakes in Scandinavia between August and September 2019. They ensured that the lakes varied in latitude, depth, area, average surface temperature and diversity of dissolved carbon-based molecules so that the results were applicable to a wider range of water bodies.
The researchers filled glass bottles with water from each lake. They then cut up plastic bags from four major UK grocery chains and shook them separately in water until the bags released the carbon compounds. A small amount of this “plastic water” was added to half of the glass bottles and an equal amount of distilled water was added to the others. After keeping the bottles in the dark for 72 hours, the bacterial activity in each of the bottles was measured.
In the “plastic water” lake water bottles, the bacteria doubled very effectively. Approximately 50 percent of this carbon was incorporated into the bacteria in 72 hours.