Bacteria That Eat One of the Most Common Plastics Has Been Discovered

March 15, 2016 | Joanne Kennell

plastic bottles, fishing net
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Could this be a solution to the world’s ever-growing plastic waste problem?

The world is obsessed with plastic. We drink from plastic water bottles and cups, we eat with plastic utensils, the foods we buy come in plastic containers or bags, and even the toys children play with are made of it. So much of what we use in our daily lives is, in some way, composed of plastic.

Plastic does not break down easily. In fact, you could call it fairly resistant to being broken down by microbes and biodegradation — taking up to 1,000 years to decompose in a landfill. However, Japanese scientists from the Kyoto Institute of Technology and Keio University may have found a breakthrough in managing the world’s plastic problem. A new species of bacteria has been discovered that can eat one of the most commonly produced plastics: polyethylene terephthalate (PET).

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50 million tonnes of PET are produced globally every year. PET makes up almost one-sixth of the world’s annual plastic production of 331 million tonnes, and according to the World Economic Forum (WEF), just over half of this is recycled and far less is reused. In addition, a third of all plastics end up in the environment and 8 million tonnes end up in the oceans every year.

A team of researchers collected 250 PET-contaminated samples including sediment, soil and wastewater from a plastic bottle recycling facility. They then screened the microbes living on the samples to determine if any of them were eating the PET and using it to grow.

The results, published in the journal Science, revealed that there were a group of microbes that appeared to break down a PET film. However, only one of the bacteria species, Ideonella sakaiensis, was responsible for PET degradation.

Further testing uncovered that the bacteria used enzymes to break down the PET, generating an intermediate chemical. The chemical was then taken up by the cell, where it was broken down even further by other enzymes, which provided the bacteria with carbon and energy needed to grow. Keeping the bacteria at a temperature of 29 degrees Celsius (84.2 degrees Fahrenheit), Ideonella sakaiensis can break down a thin film of PET in just six weeks.

Is Ideonella sakainensis the answer to the world’s ever-growing plastic waste problem? Will their discovery keep plastics out of the oceans or be an alternative to a landfill? The jury is still out.  

Dr. Tracy Mincer, who studies plastics in the ocean at the Woods Hole Oceanographic Institute in Massachusetts, told The Independent, “When I think it through, I don't really know where it gets us. I don't see how microbes degrading plastics is any better than putting plastic bottles in a recycling bin so they can be melted down to make new ones.”

However, he did note that the results could make it easier to discover other microbes with similar PET-degrading abilities: “This process could be quite common. Now that we know what we are looking for, we may see these microbes in many areas around the world.”

The use of plastic is not going away anytime soon, so we need to do our best to protect the only planet we have to call home. Don’t throw plastic in the trash — always recycle. A lot of it ends up in the oceans and at the current rate, there could be more plastic in the ocean than fish by 2050.

Do you really want to be remembered as the generation that plastified the planet?

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