Figure 1: Scientists are working with bacteria that are able to biodegrade plastic polymers into monomers.
(Source Credit: Forbes Magazine)
Since the coronavirus outbreak of 2020, the issue of plastic pollution has yet again risen to the surface.
Due to sanitary concerns, civilians have been preferred to use single-use plastics over reusable items. Along with the dramatic increase in the production of masks, the pandemic has brought us not only solitude, but also a severe accumulation–millions of plastics have filled the lands and waters of our home, the Earth (Carpenter).
Realizing the severity of the issue, numerous research centers have attempted to find a sustainable solution to counteract the matter at hand. While searching for an answer, researchers have figured that the method with the highest chance of success would be to further intensify their focus on the “plastic-eating” bacteria that were discovered a couple of years back.
Approximately 5 years ago, in March of 2016, a scientific breakthrough–which could serve as the antidote for Earth’s prolonged flu, plastic pollution–was made in Japan. A study published by the Kyoto Institute of Technology presented that the bacteria, Ideonella sakaiensis, could fractionate PET using the enzyme PET hydrolase and MHETase (Burke). Ever since this game-changing discovery was introduced to the public, many scientists thought that it would be possible to develop a method to prevent plastic pollution (Burke).
But is this really the case?
While this pioneering discovery brought immense excitement around the world, recent investigations have revealed the possibility of it being a double-edged sword.
Experts have brought attention to the fact that the large-scale commercial use of plastic-eating microorganisms are still years away, and that developing these complicated organisms is a severely time consuming process (Carpenter). Currently, the only verified bacteria is the I. sakaiensis, those of which could only degrade a specific type of plastics called PET. This bacteria also happens to be painstakingly slow at the biodegrading process, which would nearly never be able to catch up the rate at which the millions of plastics are entering our environment.
Furthermore, in order for the I. sakaiensis to function, specific conditions must be satisfied. Scientists have noted that the bacteria, who already need a prolonged time period to degrade the base level of PET, take an even longer time to degrade PET of heavily crystallized plastics. Adding an insult to an injury, most of the existing PET on our planet has already been recycled, thus, crystallized multiple times; this means that the I. sakaiensis is not a viable option to getting rid of the plastic. Another particular condition that the I. sakaiensis requires is the precision of its working temperature. Due to the bacteria having to work with certain enzymes, the optimal temperature (and in some cases, the pH) has to be set specifically in order for the bacteria to properly function (Burke).
Evolutionary barriers exist to prevent these bacteria from developing. Biologists say that it would be nearly impossible to manually find and create bacteria to biodegrade plastics, as even the earliest microbes have had millions of years to learn how to degrade natural products, such as tree barks and fruits. Plastics were first manufactured in the 1950s. Simply put, the span of approximately 70 years is not a sufficient amount of time for these bacteria to learn how to naturally degrade the plastics (Carpenter).
The upside? Researchers around the world have embarked on their journey to plummet plastic pollution–and some have returned home with successful results.
In 2017, shortly after the discovery of the I. sakaiensis, scientists reported that a fungus discovered at a waste disposal site in Islamabad, Pakistan, was able to degrade plastic. In the same year, a biology student at the Reed College in Oregon, found that samples from an oil site near her home in Houston, Texas, contained plastic-eating bacteria. Most recently, in the year of 2020, German scientists, from a brittle plastic site in Leipzig, have discovered traces of bacteria that were capable of degrading polyurethane plastic (Carpenter).
In order to intensify the benefits of these pioneering discoveries, investigations have also been conducted to make these naturally-occurring bacteria useful. In 2018, scientists investigating in the U.K. and U.S. genetically modified certain bacterias so that they could degrade bacteria in a matter of days. Last year, in October 2020, this same process was developed further by combining two different species of bacteria to produce a stronger “super enzyme” (Carpenter).
Although there have been positive results provided by the genetic manufacturing of the plastic-consuming bacteria, large-scale commercial use of such material are still long ways ahead. Researchers also mentioned that it would be increasingly difficult to degrade all types of plastics: with the less-dense, relatively easy-to-break PET already giving us a problem, they cannot imagine how arduous it would be to get rid of other types such as HDPE, a plastic thicker than PET. Additionally, the currently developed bacteria are not able to biodegrade the plastics back to their original elemental states with carbon and hydrogen; they are only capable of breaking them down into simple monomers.
Even if we do succeed in creating such a bacteria for widespread use, it would be difficult to predict the unanticipated consequences that could follow the utilization of man-made products. “Since most likely genetically engineered microorganisms would be needed, they cannot be released uncontrolled into the environment,” said Wolfgang Zimmerman, a scientist at the University of Leipzig who studies biocatalysis (Carpenter).
“Without new technologies, it’s impossible for them to meet their goals. It’s just impossible,” mentions Martin Stephan, deputy CEO of Carbios, a French environmental firm (Carpenter).
Massive technological advancements, as well as scientific research would be required to overcome the perilous issue at hand. “We can’t wait for a big breakthrough,” states Judith Enck, a former regional Environmental Protection Agency (EPA) administrator in the Obama administration and the president of Beyond Plastics, a non-profit based in Vermont (Carpenter).
Though it is the high hope of many to come across a scientific advancement, it seems that there is still an immense amount of work to be completed before we can rest assured.
Q&A:
Sally: How many years do scientists estimate would take to develop a working plastic eating bacteria? And what is the mechanism behind plastic degrading fungi?
Currently, scientists approximate that the first commercial use of degrading fungi is years away, but is in sight. However, the development of functioning plastic-eating bacteria are still generations away, due to the restraints mentioned in the article. The mechanism behind plastic degrading fungi is simply put, genetically modifying the bacteria. By rearranging the DNA of bacteria, scientists can force them to express certain characteristics that allow them to biodegrade the properties of plastics (through utilization of enzymes).
Hannah: Can the same plastic-eating bacteria be used to degrade the thicker plastics? Would a new type of bacteria need to be discovered to effectively degrade all plastic?
The same bacteria that degrades PET cannot be used to degrade thicker plastics. Infact, this is the core barrier that the researchers cannot overcome when modifying this bacteria, as they are only able to degrade the thinnest and most common type of plastics. A new type of bacteria, or a way to specifically modify the genes would be necessary to overcome these limitations.
Xavier: What exactly made Ideonella sakaiensis game-changing? Where does it come from?
As previously mentioned in the article, Ideonella sakaiensis is a game-changing bacteria, as it is the first type of bacteria that is able to “fractionate PET using the enzyme PET hydrolase and MHETase”. It comes from a 2016 study in Japan, where scientists gathered together to devise a way to mitigate the severity of plastic pollution.
John: How might the widespread usage of I.sakaiensis affect the ecosystem? Might its presence be threatening to other forms of life?
The widespread usage of Ideonella sakaiensis brings about both a positive and negative impact to our ecosystem. The positive effects being that it would theoretically be able to degrade the plastics back into simpler forms that are easier to break down. On the flipside, the negative effect would be that such rapid implementation of biodegrading bacteria may be overly drastic for our current ecosystem to handle. Although threats cannot be specifically identified for other organisms, scientists state that if the use of bacteria are globally applied, certain substances, such as carbon dioxide, may rapidly increase in the process. The sudden increase in these substances may jeopardize the well-being of other organisms.
Wooseok: In the article, several different types of organisms capable of degrading plastic were mentioned. Do they have all similar methods of degrading plastic?
Although the article only specified one type of bacteria, called the Ideonella sakaiensis, researchers are currently working to discover additional types of bacteria in order to tackle the degradation of diverse plastics. The current type is only able to degrade the thinnest type called the PET; thus, if other types were to be contrived, they would most likely be targeted to break down other thicker and less-common types of plastics.
Anna: You mentioned “unanticipated consequences” of man-made products. What are some examples of those consequences?
One of these negative consequences could be that biodegrading the polymers that comprise the plastics risks releasing chemical additives that are normally stored up in the original, pre-degraded plastics. Scientists add on by stating that there are potential unknown side-effects of implementing widespread use of these bacterias, as it would be the first time releasing these genetically bioengineered organisms into an environment majorly consisting of natural products.
Fabian: Would it be possible to extract the genes/features that allow the organisms to degrade plastic and mass-produce only that trait for wider and quicker usage?
It is exceedingly difficult to extract the specific genes and modify certain parts of the bacteria’s DNA, as it would mean that it requires modification of such precise and minuscule data. Simply put, it would be nearly impossible to extract certain features from these organisms. Additionally, scientists mentioned that utilizing selective breeding would also take an extended amount of time (generations) in order to achieve the desired results.
Works Cited
Burke, Cara. “Plastic Eating Bacteria: A Viable Solution to the Plastic Problem?: Earth.org - PAST: Present: Future.” Edited by Owen Mulhern, Earth.Org - Past | Present | Future, Earth.Org, 15 Mar. 2021, earth.org/data_visualization/plastic-eating-bacteria-a-viable-solution-to-the-plastic-problem/.
Carpenter, Scott. “The Race to Develop Plastic-Eating Bacteria.” Forbes, Forbes Magazine, 17 Mar. 2021, www.forbes.com/sites/scottcarpenter/2021/03/10/the-race-to-develop-plastic-eating-bacteria/?sh=3e3ce30e7406.
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