According to a study, microbes in soils and oceans around the world are evolving to eat plastic.
The research identified more than 200m genes in DNA samples from the environment. It found 30,000 different enzymes capable of degrading 10 types plastic.
The study is the world’s first large-scale global assessment on the plastic-degrading capacity of bacteria. It found that only one in four organisms examined had a suitable enzyme. Researchers found that the amount and type corresponding enzymes found in the organisms corresponded to the levels and types of plastic pollution at different locations.
The scientists concluded that the results showed evidence of a tangible effect of plastic pollution on global microbial ecology.
Every year, millions of tonnes of plastic are dumped into the environment. This pollution has now spread to every corner of the globe, from the top of Mount Everest to deepest oceans. It is important to reduce the amount of plastic and properly collect and treat waste.
However, many plastics are difficult to degrade or recycle. Enzymes that rapidly break down plastics would allow for new products to be made using old ones. This would reduce the need to produce virgin plastic. New enzymes are being discovered and modified for industrial use.
Multiple evidence points were found supporting the conclusion that the global microbiomes plastic degradation potential correlates strongly to environmental plastic pollution measurements. This is an important demonstration of how the environment responds to the pressures placed on it, stated Prof Aleksej Zelezniak from Chalmers University of Technology, Sweden.
Jan Zrimec, also from Chalmers University, stated: We didn’t expect to find such an extensive range of enzymes across so diverse microbes and environmental environments. This is a remarkable discovery that really demonstrates the magnitude of the problem.
Researchers stated that the plastic boom of the past 70-years, which saw plastic production rise from 2m tonnes to 385m tonnes per year, had allowed microbes to adapt to plastic. The study, Published in the journal Microbial EcologyWe started by compiling a list of 95 microbial enzymes that are already known to degrade plastic. These enzymes are often found in bacteria in garbage dumps and other places rife in plastic.
The team then looked for similar enzymes from environmental DNA samples taken from 236 locations around the globe by other researchers. The researchers also compared the enzymes they had initially identified with enzymes taken from the human stomach, which is not known for having any plastic-degrading enzymes.
The new enzymes were discovered in ocean samples taken at 67 locations and at three depths. The results showed that the levels of degrading enzymes found at deeper levels were consistently higher than those found at lower levels. This is consistent with the higher levels of plastic pollution at lower depths.
The soil samples came from 169 locations across 38 countries and 11 habitats. 18,000 plastic-degrading enzymes were found in the soil samples. The soils are more likely to contain phthalate additives than oceans, and the researchers discovered more enzymes that could attack these chemicals in the soil samples.
Scientists found that nearly 60% of the new enzymes didn’t fit into any existing enzyme classes. This suggests that these molecules can degrade plastics in ways previously unknown.
Zelezniak said that the next step would be to test promising enzyme candidates in a laboratory to examine their properties and determine the rate of plastic degradation they can achieve. This will allow you to create microbial communities capable of degrading specific types of polymers.
In 2016, the first insect that eats plastic was found in a Japanese landfill. It was discovered in a Japanese landfill in 2016. Scientists modified it in 2018 to find out more about its evolution, but accidentally created an enzyme that is even better at breaking down plastic bottles. Further tweaks were made in 2020 to increase the speed of degradation sixfold.
Carbios created a second mutant enzyme in 2020 that quickly breaks down plastic bottles and can be recycled. German scientists also discovered that a bacterium feeds off toxic plastic polyurethane which is commonly dumped in landfills.
Scientists revealed last week that microplastics found in human food can cause damage to human cells.