In the guide below, we provide a range of information on plastic eating bacteria.
We outline what they are, how they work, when they were discovered & how they have developed, potential pros and cons, how much they may help with plastic problems, and more.
Summary – Plastic Eating Bacteria
The first bacteria with an enzyme naturally evolved to degrade plastic was discovered in 2016.
Since that time, there’s been several developments in the field of ‘plastic eating bacteria’ and their enzymes, including the speed at which they degrade plastics, and also the range of materials they might be able to break down.
There might be a range of potential pros and cons to plastic eating bacteria, which we list in the guide below.
At this stage however, they might be limited in their application, and only be one of many potential solutions/options to address plastic problems like plastic pollution.
As of recently, studies have shown that more bacteria might naturally be evolving to digest plastic, as more plastic digesting enzymes are being found in different locations in the environment across the world (such as oceans and soils).
In addition to bacteria, there may be other organisms that eat or degrade bacteria too.
What Are Plastic Eating Bacteria?
They are strains of bacteria that have the ability to break down (decompose) and consume certain types of plastic (like PET)
They also have the ability to use plastic for energy, or turn it to carbon dioxide and release it
Examples Of Plastic Eating Bacteria
wikipedia.org identifies that ‘Ideonella sakaiensis’ is an example of a bacterium capable of breaking down and consuming the plastic PET, and ‘using it as both a carbon and energy source’
How Do Plastic Eating Bacteria Work?
In general, plastic eating bacteria might work in the following way:
– Firstly, once the bacteria has adhered itself to the plastic and found accessible plastic molecules, the bacteria secrete the PETase enzyme. PETase breaks down/degrades PET long polymers in PET products like plastic bottles. It does this by splitting the chemical bonds/links (known as esters) in the polymer chain
– A second enzyme – the MHETase enzyme – then finishes the break down process of plastic into into ‘monomeric constituents’. wikipedia.org mentions that PETase was genetically modified and combined with MHETase to break down PET faster
– These monomeric constituents can then be ‘taken up’ (i.e. consumed, or absorbed) by the bacteria
– Molecules from the PET plastic item that have been taken up by the bacteria after degradation might be used to produce energy, build biomolecules, or might be ‘mineralized to carbon dioxide and released into the atmosphere’
wikipedia.org includes a much more detailed breakdown and explanation of how the Ideonella sakaiensis bacterium breaks down and takes in PET plastic
theconversation.com also provides more information specifically on what study papers show about how the PETase protein works, and also it’s structure
When Were Plastic Eating Bacteria Discovered?
They are a reasonably recent discovery.
Multiple reports indicate that Japanese scientists accidentally discovered bacteria that could decompose plastic in 2016, after they analysed mud/sludge near a plastic recycling factory.
theconversation.com indicates that the PETase enzyme used by this bacteria ‘… evolved specifically [to digest PET plastic]’, which makes the discovery unique
wikipedia.org mentions how there were degraders of PET before the discovery of Ideonella sakaiensis (the bacteria discovered by Japanese scientists), but these degraders did not do so as ‘… a primary carbon and energy source’
Where Is The Research & Development For Plastic Eating Bacteria At Now?
Since the discovery of plastic eating bacteria in 2016, some of the developments in plastic eating bacteria include but aren’t limited to:
– In 2018, a paper was published that indicated that scientists were able to engineer and improve bacteria to make it work faster, however, the result of this hasn’t been significant to this point (theguardian.com mentions the improvement was about 20%)
wikipedia.org notes that genetic modification of PETase and combination with MHETase allowed PET to be broken down faster
– In 2020, a ‘super-enzyme’ that could degrade plastic bottles six times faster was created by scientists, and there were both other developments, and ongoing developments related to this work
Potential Pros & Cons Of Plastic Eating Bacteria
Potential Pros
Evolved enzymes in bacteria may offer new recycling possibilities and other waste or pollutant treatment options
For example, several reports note that the PETase enzyme evolved specifically for PET digestion in the bacteria Ideonella sakaiensis, might have the potential for use in bio recycling
In this example, enzymes from the bacteria may at some point be able to be used in bio reactors (to break down plastic)
Bacteria might also be used in bioremediation
wikipedia.org also notes how Ideonella sakaiensis is being studied for it potential use as an anti pollutant for sewage fed fisheries, and in other environments where waste water and polluted waters may be an issue
May help make recycling some types of plastic recycling more sustainable/eco friendly by removing parts of the plastic recycling process
Such as using collection trucks, transporting plastic, plastic recycling equipment, and so on
Genetic modification and further improvement of bacterial enzymes may present new options for managing plastic waste
For example, wikipedia.org mentions that GE of bacterial enzymes and other approaches may present possibilities with ‘… recycling and upcycling of mixed plastics’ in the future, and GE has already helped with the degradation of PET plastics
theguardian.com further explains how developments with bacteria and their enzymes may present more options for waste management in the future, such as breaking down mixed materials
Potential Cons
At this point in time, the results from plastic eating bacteria aren’t significant enough for them to be a significant or complete solution to plastic pollution and other plastic problems
For example:
– They aren’t used on a large scale yet
– They can only break down certain types of plastic at this point in time
– There’s debate as to whether they are completely degrading the plastic, or whether there are leftover plastic fragments after breakdown
cen.acs.org notes that at this point in time:
Most reported cases of an enzyme … degrading plastic are incomplete and slow
[And, there needs to be evidence in each case that bacteria are] biochemically degrading the polymer rather than simply shredding it
There may be challenges in using bacteria or their enzymes for plastic recycling or to break down plastic in the future
– Cost
cen.acs.org notes that costs for plastic degrading bacteria have to be able to compete with other technologies like ‘… chemical recycling methods and virgin monomers’
– Some Plastics Are Hard To Break Down
theconversation.com for example mentions how the physical properties of plastic make it difficult for enzymes to react with the material – because of how tightly plastic molecules are packed in PET’s structure, enzymes may have a difficult time getting to them
This might be the case specifically if enzymes are trialled for use in bio reactors for plastic recycling
Enzymes ultimately need easily accessible plastic molecules to break down
cen.acs.org explains this further, noting how some plastics are much more challenging to break down (especially those with higher crystallinity)
– Bacteria Surviving In Different Environments
Additionally, some bacteria can only grow and survive in certain environments, such as aerobic bacteria only being able to survive in places where there is available oxygen.
So, there may be limitations in the places where bacteria can decompose plastic.
wikipedia.org for example mentions that Ideonella Sakaiensis are ‘… known to survive in oxygen-rich soil that is moist and aerated’
Bacteria may still release carbon from the plastic into the atmosphere as carbon dioxide, and some bacteria may release other potentially non eco friendly substances like toxins
This is an environmental/sustainability consideration
Plastic eating bacteria may be a problem for plastic we don’t want it to eat
The more bacteria (and their enzymes) naturally evolve to eat plastic, or the more they are engineered to improve their plastic eating ability, the more of a problem plastic material that we want to stay in tact may have
If bacteria are released into the ocean to address plastic pollution for example, and they spread in the wild, structures and items that contain plastic that we use for everyday life, such as building as one example, may be at risk of being contaminated with this bacteria and they may be at risk of degrading
How Much Can Plastic Eating Bacteria Actually Help With Plastic Problems (Like Plastic Pollution)?
As we identified above, plastic eating bacteria may help in some ways.
But, their effectiveness, the scale at which they can be used, and the range of plastics they can currently break down and consume might be limited.
Therefore, at this point in time, plastic eating bacteria may only be one of many solutions that have to be implemented to address plastic problems like plastic pollution, and other plastic related problems.
Have Plastic Eating Bacteria Been Found In The Ocean?
According to sustainablefootprint.org, bacteria that were found to be breaking down plastic were found in a part of the North Atlantic Ocean, however, there’s uncertainty over whether the by-product of breaking down the plastic is eco friendly or a toxin
Where Else Are Plastic Eating Bacteria & Enzymes Found?
discovery.com mentions that a range of bacteria in soils and oceans in different parts of the world might be evolving to digest plastic, as enzymes that can break down plastic appear to match the enzymes found in some of these environments in the wild.
Over 18,000 plastic-eating enzymes were found in soil alone, and about 12,000 in the ocean.
theguardian.com notes that based on the study ‘… one in four of the organisms analysed carried a suitable enzyme [for plastic degradation potential]’
Other Potential Plastic Eating Organisms
In this guide, we list and discuss some of the other potential plastic eating organisms apart from bacteria.
Sources
1. https://theconversation.com/how-plastic-eating-bacteria-actually-work-a-chemist-explains-95233
2. https://en.wikipedia.org/wiki/Ideonella_sakaiensis
3. https://www.forbes.com/sites/scottcarpenter/2021/03/10/the-race-to-develop-plastic-eating-bacteria/?sh=540148b07406
4. https://www.theguardian.com/environment/2018/apr/16/scientists-accidentally-create-mutant-enzyme-that-eats-plastic-bottles
5. https://rsscience.com/plastic-eating-bacteria/
6. https://oceanblueproject.org/plastic-eating-enzyme/
7. https://sustainablefootprint.org/en/plastic-eating-bacteria-in-the-oceans/
8. https://www.theguardian.com/environment/2020/sep/28/new-super-enzyme-eats-plastic-bottles-six-times-faster
9. https://www.theguardian.com/environment/2018/apr/16/scientists-accidentally-create-mutant-enzyme-that-eats-plastic-bottles
10. https://www.discovery.com/science/thousands-of-bacterial-enzymes-hold-the-key-to-plastic-pollution
11. https://www.theguardian.com/environment/2021/dec/14/bugs-across-globe-are-evolving-to-eat-plastic-study-finds
12. https://cen.acs.org/environment/sustainability/Plastics-recycling-microbes-worms-further/96/i25
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