Chinese scientists discover plastic-eating bacteria

A team of researchers in China claims to have found marine bacteria capable of breaking down polythene, which is found in many plastic products worldwide and the source of much of the pollution in the oceans.

In 2010, global plastic waste was estimated to be around 275 million tonnes per year, exceeding annual production at that point in time.

2020 numbers estimate as many as 500 billion plastic bags are used every year - equating to roughly 150 per person on Earth - and National Geographic predicts the amount of plastic entering the world's oceans will triple by 2040 to 29 million metric tonnes annually if nothing is done to stop the spread.

Read more: A mutant enzyme that breaks down plastic in hours

The concept of plastic-eating enzymes is not new to the scientific community. A number of projects in the past have looked to testing such ideas in order to help tackle the issues of existing plastic waste alongside other more permanent solutions such as the adoption of a circular economy.

The report, published in the Journal of Hazardous Materials on April 24 and led by Sun Chaomin, a Professor for the Institute of Oceanology at the Chinese Academy of Sciences, claims to have found a string of bacteria that can break down both polyethylene terephthalate (PET) - found in most plastic bottles - but also polythene (PE), found in plastic bags.

If effective, the bacteria could stand to tackle a large amount of the plastic pollution the world currently faces.

"Our study establishes a stable marine bacterial community that efficiently degrades PET and PE and provides insights into plastic degradation pathways and their associated biological and mechanistic processes—paving the way for developing microbial products against plastic wastes," the report's authors said.

“Compared to the extensive studies into PET-degrading bacteria and enzymes, research into PE degradation lags well behind,” they added.

The study used a screening approach on hundreds of plastic-waste associated samples and eventually found a collection of three bacteria that were able to cause "obvious damage" to the plastics, including cracks and "deep holes" on both the surface and inside the films.

Roughly 300 samples of plastic waste were collected from Huiquan Bay, the authors added, with the samples being kept at room temperature.

The report claims PE and PET plastics constitute a majority of the world's plastic pollution.

The bacteria used in the study are currently in the process of being genome sequenced, potentially allowing for replication to allow for microbial products to be created.

Worldwide, only 9% of the total manufactured plastic has ever been recycled.

Read more: An innovative solution to the problem of plastic waste

There are currently five major buildups of plastic in the world's oceans, according to Dutch NGO The Ocean Cleanup. The largest, colloquially referred to as the "Great Pacific Garbage Patch," clocks in at around 1.6 million square miles - slightly larger than Mongolia. If it were a nation, it would be the 18th largest in the world.

"The stronger, more buoyant plastics show resiliency in the marine environment, allowing them to be transported over extended distance," according to the NGO. 

It added: "They persist at the sea surface as they make their way offshore, transported by converging currents and finally accumulating in the patch."

The NGO recently published a study reporting that as much as 80% of the plastic in the world's rivers drains into the sea.

Boyan Slat, founder and CEO of The Ocean Cleanup, said: “While the plastic problem may seem daunting in scale, this updated understanding of where plastic becomes ocean plastic will allow for a much more targeted intervention.

"As we see huge differences in pollution levels across the globe, these results could help to rapidly increase the speed of solving the problem. We will use this new data as a guide for our cleanup activities, and we hope others will too.”

A 2018 report by Plastics Europe reported that 350 million tonnes of plastics are produced worldwide annually, with half becoming waste in less than a year.

Plastic waste also represents a huge economic loss with $120 billion (€101.8 billion) wasted per year according to the World Economic Forum.

Much of the pollution comes from companies such as Cola-Cola, Nestlé and PepsiCo, according to Break Free From Plastic's yearly audits.

Many of these companies have since sworn to cut down on plastic pollution, but the results remain to be seen.

Companies such as Unilever, which ranked fourth place in last year's audit, have committed to plastic recycling as part of their business models in order to tackle this crisis.

Read more: Unilever NA invests $15 million in plastics recycling

The circular economy will only aid in plastics that are recycled or for the results of any future production. Bacteria such as those present in the study may be required in order to tackle the issue of existing waste.

Scientists in this field have a good idea of how plastic waste is broken down, but finding the right enzymes to accomplish this remains their primary focus.

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