Sofia Martinez
The discovery of bacteria that can break down plastics has spurred discussions about their potential use in recycling and bioremediation. While the idea of using bacteria to break down plastics is not new, recent findings have identified specific enzymes produced by these bacteria that enable them to degrade plastics more efficiently. This has led to the development of genetically modified bacteria that can break down plastics in saltwater, addressing the challenge of plastic pollution in oceans. These advancements open up new possibilities for bacteria-based engineering solutions to tackle the growing problem of plastic waste.
| Characteristics | Values |
|---|---|
| Bacteria that breaks down plastic | Ideonella sakaiensis |
| How it works | The bacterium uses a secreted PET hydrolase, or PETase, to degrade the PET into mono(2-hydroxyethyl)terephthalic acid (MHET) |
| How it was discovered | Kohei Oda and his team discovered the bacterium in a rubbish dump in Sakai City, Japan |
| Genetically modified variant | Researchers have genetically engineered a marine microorganism by combining Ideonella sakaiensis with Vibrio natriegens to break down plastic in saltwater |
| Feasibility | Feasible, but additional hurdles must be addressed |
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What You'll Learn
- Ideonella sakaiensis, a bacterium that breaks down PET plastic
- Genetically modified bacteria that can break down plastics in saltwater
- Comamonas testosteroni, a wastewater bacterium that breaks down plastic for food
- The potential for bacteria-based engineering solutions to clean up plastic waste
- The discovery of bacteria that break down plastic and their importance in recycling
Ideonella sakaiensis, a bacterium that breaks down PET plastic
Ideonella sakaiensis is a bacterium from the genus Ideonella and family Comamonadaceae. It was first identified in 2016 by a team of researchers led by Kohei Oda of the Kyoto Institute of Technology and Kenji Miyamoto of Keio University. The bacterium was isolated from a sediment sample taken outside a plastic bottle recycling facility in Sakai City, Japan.
I. sakaiensis is capable of breaking down and consuming polyethylene terephthalate (PET) plastic. It uses a secreted PET hydrolase, or PETase, to degrade the PET into mono(2-hydroxyethyl)terephthalic acid (MHET). The PETase also degrades PET into another intermediate known as Bis-(2-hydroxyethyl) terephthalate (BHET), which can be further converted into MHET after PET hydrolysis. The resulting MHET is then degraded into its two monomeric constituents by a lipid-anchored MHET hydrolase enzyme, or MHETase, on the cell's outer membrane. These monomeric constituents are then taken up and used by I. sakaiensis and many other bacteria.
The discovery of I. sakaiensis has important implications for the degradation of PET plastics. Prior to its discovery, only a small number of bacteria and fungi were known to degrade PET, and none were definitively known to use it as a primary carbon and energy source. I. sakaiensis is able to colonize and break down thin films of low-crystallinity PET in approximately six weeks. However, it degrades high-crystallinity PET much slower (30 times slower, or more than 3 years).
The PETase enzyme produced by I. sakaiensis has been genetically modified and combined with MHETase to break down PET faster and also degrade PEF (polyethylene furanoate) plastics. This approach may be useful in recycling and upcycling mixed plastics. For example, in 2021, a coagulation filtration system concept was created using I. sakaiensis to filter, coagulate, flocculate, and sediment water in a more environmentally friendly and efficient way.
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Genetically modified bacteria that can break down plastics in saltwater
The feasibility of using bacteria to break down plastics has been a topic of interest for researchers for many years. In 2023, researchers from North Carolina State University genetically engineered a marine microorganism to break down plastics in saltwater. The modified organism can break down polyethylene terephthalate (PET), a plastic used in everything from water bottles to clothing that significantly contributes to microplastic pollution in oceans.
The researchers worked with two species of bacteria. The first bacterium, Vibrio natriegens, thrives in saltwater and reproduces very quickly. The second bacterium, Ideonella sakaiensis, produces enzymes that allow it to break down and metabolize PET. Ideonella sakaiensis was first identified in 2016 by a team of researchers led by Kohei Oda of the Kyoto Institute of Technology and Kenji Miyamoto of Keiu University. They discovered the bacterium in a sediment sample taken outside a plastic bottle recycling facility in Sakai City, Japan.
To create the genetically modified organism, the researchers took the DNA from I. sakaiensis that is responsible for producing the enzymes that break down plastic and incorporated that genetic sequence into a plasmid. Plasmids are genetic sequences that can replicate in a cell independently of the cell's own chromosome. By introducing the plasmid containing the I. sakaiensis genes into V. natriegens, the researchers were able to get V. natriegens to produce the desired enzymes on the surface of their cells. The researchers then demonstrated that V. natriegens could break down PET in a saltwater environment at room temperature.
The researchers acknowledged that additional challenges must be addressed. One challenge is to incorporate the DNA from I. sakaiensis directly into the genome of V. natriegens to make the production of plastic-degrading enzymes more stable. Another challenge is to modify V. natriegens so that it can feed on the byproducts it produces when it breaks down PET. Lastly, the researchers aim to modify V. natriegens to produce a desirable end product from PET, such as a molecule that could be useful to the chemical industry.
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Comamonas testosteroni, a wastewater bacterium that breaks down plastic for food
The feasibility of using bacteria to break down plastic is a promising prospect in the fight against plastic pollution. A common environmental bacterium, Comamonas testosteroni, has been found to break down plastic for food. This discovery opens up new possibilities for bacteria-based engineering solutions to tackle plastic waste.
Comamonas testosteroni, a wastewater bacterium, has a unique appetite for complex waste from plants and plastics, unlike most bacteria, which prefer sugars. This bacterium was first noticed for its ability to digest synthetic laundry detergents. Further analysis revealed that it can also break down compounds from plastic and lignin (fibrous, woody waste from plants). Comamonas species are found in diverse environments, including soils and sewage sludge.
The process by which C. testosteroni breaks down plastic has been the subject of recent research. It was found that the bacterium first chews the plastic into small pieces called nanoplastics. It then secretes a specialized enzyme that further breaks down the plastic. Finally, the bacterium utilizes a ring of carbon atoms from the plastic as a food source. This process of breaking down plastic into nanoparticles makes the carbon bioavailable for bacterial growth.
The discovery of C. testosteroni's ability to degrade plastic has significant implications for recycling plastic waste. Researchers can now explore the use of this bacterium in biotechnology platforms to harness its plastic-degrading capabilities. By understanding the metabolic mechanisms of C. testosteroni, scientists can develop innovative ways to address the global issue of plastic pollution.
While C. testosteroni shows promise in breaking down plastic, there are other bacterial species that have also been studied for their plastic-degrading abilities. Ideonella sakaiensis, for example, is a bacterium that can break down and consume polyethylene terephthalate (PET), a common plastic. This discovery has spurred discussions about using bacteria for PET biodegradation and recycling. By genetically modifying enzymes and combining different bacterial species, researchers are working towards more efficient plastic degradation.
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The potential for bacteria-based engineering solutions to clean up plastic waste
The discovery of plastic-eating bacteria has opened up new possibilities for bacteria-based engineering solutions to tackle plastic waste. This discovery is especially important given the scale of plastic pollution, with 2.5 billion tonnes of plastic waste generated in the last 20 years and an annual production of 380 million tonnes, projected to triple by 2060.
One such bacterium, Ideonella sakaiensis, was discovered in a rubbish dump in Sakai City, Japan, in 2016. This bacterium can break down and consume polyethylene terephthalate (PET), a common plastic used in packaging and clothing, using it as a carbon and energy source. The discovery of I. sakaiensis spurred discussions about PET biodegradation as a recycling and bioremediation method.
Further research has focused on the PETase enzyme produced by I. sakaiensis, which breaks down PET. Scientists have genetically engineered this enzyme to combine it with MHETase, resulting in faster degradation of PET and PEF (polyethylene furanoate) plastics. This approach could be beneficial for recycling and upcycling mixed plastics.
Additionally, researchers have combined the traits of two bacterial species, Vibrio natriegens and I. sakaiensis, to create a modified organism that can break down PET in saltwater. This is significant as it addresses the challenge of removing plastics from the ocean and treating them before breaking them down.
Another study by Northwestern University has revealed that a common bacterium, Comamonas testosteroni, can break down plastic for food. This bacterium grows on PET, a major contributor to plastic pollution, and uses a specialized enzyme to break it down into nanoplastics.
These findings demonstrate the potential for bacteria-based engineering solutions to address plastic waste. Further research and development are needed to optimize these solutions and make them practical for tackling the global plastic pollution crisis.
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The discovery of bacteria that break down plastic and their importance in recycling
The world is facing a plastic crisis. Only 9% of the plastic ever made has been recycled, with the rest ending up in landfills and waterways. Every year, about 380 million tonnes of plastic waste are produced, with that amount projected to triple by 2060. This has led to a search for solutions to the plastic crisis, including the use of microorganisms like bacteria to break down plastic.
In 2016, a team of researchers led by Kohei Oda of the Kyoto Institute of Technology and Kenji Miyamoto of Keio University discovered a bacterium, Ideonella sakaiensis, capable of breaking down and consuming polyethylene terephthalate (PET), a common plastic used in packaging and bottles. The bacterium was isolated from a sediment sample taken outside a plastic bottle recycling facility in Sakai City, Japan. Ideonella sakaiensis uses a secreted PET hydrolase, or PETase, to degrade PET into mono(2-hydroxyethyl)terephthalic acid (MHET). The PETase also degrades PET into another intermediate known as Bis-(2-hydroxyethyl) terephthalate (BHET), which can be converted into MHET after PET hydrolysis. The resulting MHET is then degraded into its two monomeric constituents, ethylene glycol and terephthalic acid, by a lipid-anchored MHET hydrolase enzyme, or MHETase, on the cell's outer membrane. These monomeric constituents can then be used by Ideonella sakaiensis and other bacteria for growth.
The discovery of Ideonella sakaiensis has important implications for the degradation and recycling of PET plastics. Prior to its discovery, only a small number of bacteria and fungi were known to degrade PET, and no organisms were definitively known to use it as a primary carbon and energy source. Ideonella sakaiensis is able to break down thin films of low-crystallinity PET in approximately six weeks. While this is impressive, it is still too slow to have a significant impact on plastic waste at scale. However, scientists have become proficient at engineering and manipulating enzymes, and the PETase enzyme produced by Ideonella sakaiensis has been genetically modified to break down PET faster. This modified enzyme has been combined with MHETase, and this approach may be useful in recycling and upcycling mixed plastics.
The discovery of Ideonella sakaiensis and its ability to break down PET has spurred discussion about PET biodegradation as a method of recycling and bioremediation. A French company, Carbios, has been using a bacterial enzyme to process PET plastic waste, breaking it down into its precursor molecules, which can then be made into new plastic. This brings us closer to achieving infinitely recyclable plastics. While there are limitations to the types of plastics that can be efficiently enzymatically digested, the discovery of Ideonella sakaiensis and its PETase enzyme has opened up new possibilities for recycling and upcycling mixed plastics, bringing us a step closer to solving the world's plastic problem.
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Frequently asked questions
Plastic-eating bacteria are microorganisms that can break down plastic into basic nutrients.
The bacteria use enzymes to break down the plastic into smaller pieces, which are then further broken down into their precursor liquids.
Ideonella sakaiensis is a bacterium that can break down and consume the plastic polyethylene terephthalate (PET). Comamonas testosteroni is another example of a bacterium that can grow on and break down PET.
Plastic-eating bacteria could be used to develop bacteria-based engineering solutions to help clean up plastic waste in the environment, including in saltwater and freshwater environments.
