Plastic ‘Eaters’

We, as humankind, are in the midst of a ‘Great Plastic Age’ – and its effects will last across the ages (see the Plastics section for more information). The most prevalent issue with plastic production is the problem of disposal, with many plastics estimated to degrade over the course of centuries or millennia, if ever. Have you ever used and disposed of a polyester PET water bottle? Then you’ve already left your own personal legacy, as PET (Polyethylene terephthalate) does not naturally biodegrade.

Plastic degradation times
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Chances are, if you’ve already reached this website, you are aware of the devastating effect our plastic waste has on the ecosystem. If we could stop producing so much plastic, that would be a tremendous aid; however, we are past the point of no return, with plastic lifespans exceeding our lifespans by  far.

Luckily, bacterium has been discovered in 2016 that has naturally evolved to eat plastic (read the fascinating original article here). Since that day, scientist have been scrambling to use this knowledge to create a viable and efficient disposal system for plastics.

The bacterium, Ideonella sakaiensis, was discovered near a Japanese bottle-recycling dump and has also been spotted in some other PET-polluted sites. It is not only capable of breaking the molecular bonds of PET (polyester), but thrives on it. For those of the chemical mind: the strain, when grown on polyester plastic, produces two different enzymes that can hydrolyze PET as well as its reaction intermediate, which efficiently converts PET into two monomers (terephthalic acid and ethylene glycol). To clarify, the bacterium can live on the low-quality plastic, secreting two natural catalysts that break down the PET to its environmentally safe components.

Ideonella sakaiensis
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Since this discovery, researchers have examined the structure of the I. sakaiensis produced enzymes, trying to figure out how such a strain could have evolved in response to our plastic crisis. Yet instead of an understanding of history, they accidentally tweaked an enzyme in such a way that they improved it…by 20%. While this is impressive, it also indicates that this newly encountered bacteria is also not fully optimized. Perhaps in years to come, we can use bacteria and enzymes as an ecologically safe alternative to harsher industrial catalysts. In fact, patents have already been filed by the researchers at the University of Portsmouth as well as by the US National Renewable Energy Laboratory in Colorado.

This is quite the difference from another strain of bacteria found in 2015 – Fusarium oxysporum cutinase (FoCut5a) – a fungus enzyme that has also been found to ‘eat’ PET plastics. For one, it is already much more efficient. Additionally, bacteria are much easier to control in industrial environments than fungi. In a scientific field that is constantly battling the cheap methods of ‘fresh’ plastic, economic constraints are highly applicable.

Despite changing public opinion, at this moment in time true change will need the support of our resistant governments and businesses.

There may still be a long way to go before we are truly capable of harnessing the rapid power of enzymes, but studies are indicating more and more that it is possible. If we could change the I. sakaiensis bacteria to survive at extreme conditions (above 70 C), for example, then we could degrade PET in its viscous, rather than glassy state, and improve degradation times by 10-100%.

What is truly fascinating is the popular theory that many of these strains may have evolved in response to the current plastic crisis. Perhaps with an open mind and powerful scientific teams we can discover more of these gifts and aids nature is providing us with.

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Plastics

Surfrider Foundations
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From micro-plastics to the Great Pacific Garbage Patch, everyone is aware of the scope of humankind’s plastic waste. It has long been known that plastic materials have been found in seafood, but new research has elaborated on how far plastic can permeate. Plastic bags have been found as far as the Mariana Trench, and studies have shown micro-plastics prevalent in our tapwater and salt. A recent study from Purdue University in Aug. 2018 studied 159 tap water samples across the globe, finding that at least 81% were contaminated, mostly with fibers between 0.1-5mm in length.

Plastics Map
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Another study completed 2015 in Shanghai, China researched the extent of micro-plastics in commercial table salt. From the 15 brands of samples taken from Chinese ocean coastal areas, lakes, and wells, sea salts were found to have a much higher content of plastic particles per kilogram (550–681 particles/kg in sea salts, 43–364 particles/kg in lake salts, and 7–204 particles/kg in rock/well salts).

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This signals the abundance of micro-plastic contamination that occurs in the ocean, primarily polyethylene terephthalate, polyethylene, and cellophane.

A 2017 study also researched micro-plastic contamination in 17 table salt brands across 8 different countries: while micro-plastics were absent in one brand, others contained various plastic polymers , pigments, and amorphous carbon.

While the amount of micro-plastic in salt is negligible in terms of consumption health risks, this data indicates a gradual accumulation of contamination in the ocean, with little understanding of future consequences. Micro-plastics at sea have been discovered to host micro-organisms and could serve as a new habitat for potential pathogens, which can be spread and ingested globally.

Our epoch will be recorded for centuries to come, as the artifacts of our disposable lifetime remain, resisting decomposition. If the Holocene era was named to include both Bronze and Iron Ages, then ours will be called the Great Plastic Era.

However, at least with this nomenclature comes the realization that our generation faces a problem that simply isn’t going away. And through this understanding we can start to outline some solutions.

Explore Alternate Techniques for new scientific methods and concepts, and What You Can Do to find out how you can help as an individual.