These bacteria eat plastic - TED TALK TRANSCRIPT

Morgan Vague |TEDxMtHood • October 2018

Humans produce 300 million tons of new plastic each year -- yet, despite our best efforts, less than 10 percent of it ends up being recycled. Is there a better way to deal with all this waste? Morgan Vague describes her research with microbiologist Jay Mellies on bacteria that have evolved the unexpected ability to eat plastic -- and how they could help us solve our growing pollution problem.

Plastics: you know about them, you may not love them, but chances are you use them every single day. By 2050, researchers estimate that there will be more plastic in the ocean than fish.

00:20

Despite our best efforts, only nine percent of all plastic we use winds up being recycled. And even worse, plastic is incredibly tough and durable and researchers estimate that it can take anywhere from 500 to 5,000 years to fully break down. It leaches harmful chemical contaminants into our oceans, our soil, our food, our water, and into us.

00:52

So how did we wind up with so much plastic waste? Well, it's simple. Plastic is cheap, durable, adaptable, and it's everywhere. But the good news is there's something else that's cheap, durable, adaptable and everywhere. And my research shows it may even be able to help us with our plastic pollution problem.

01:16

I'm talking about bacteria. Bacteria are microscopic living beings invisible to the naked eye that live everywhere, in all sorts of diverse and extreme environments, from the human gut, to soil, to skin, to vents in the ocean floor, reaching temperatures of 700 degrees Fahrenheit. Bacteria live everywhere, in all sorts of diverse and extreme environments. And as such, they have to get pretty creative with their food sources. There's also a lot of them. Researchers estimate that there are roughly five million trillion trillion -- that's a five with 30 zeros after it -- bacteria on the planet. Now, considering that we humans produce 300 million tons of new plastic each year, I'd say that our plastic numbers are looking pretty comparable to bacteria's.

02:17

So, after noticing this and after learning about all of the creative ways that bacteria find food, I started to think: could bacteria in plastic-polluted environments have figured out how to use plastic for food? Well, this is the question that I decided to pursue a couple of years ago. Now, fortunately for me, I'm from one of the most polluted cities in America, Houston, Texas.

02:47

In my hometown alone, there are seven EPA-designated Superfund sites. These are sites that are so polluted, that the government has deemed their cleanup a national priority. So I decided to trek around to these sites and collect soil samples teeming with bacteria. I started toying with a protocol, which is fancy science talk for a recipe. And what I was trying to cook up was a carbon-free media, or a food-free environment. An environment without the usual carbons, or food, that bacteria, like us humans, need to live.

03:27

Now, in this environment, I would provide my bacteria with a sole carbon, or food, source. I would feed my bacteria polyethylene terephthalate, or PET plastic. PET plastic is the most widely produced plastic in the world. It's used in all sorts of food and drink containers, with the most notorious example being plastic water bottles, of which we humans currently go through at a rate of one million per minute. So, what I would be doing, is essentially putting my bacteria on a forced diet of PET plastic and seeing which, if any, might survive or, hopefully, thrive.

04:14

See, this type of experiment would act as a screen for bacteria that had adapted to their plastic-polluted environment and evolved the incredibly cool ability to eat PET plastic. And using this screen, I was able to find some bacteria that had done just that. These bacteria had figured out how to eat PET plastic.

04:40

So how do these bacteria do this? Well, it's actually pretty simple. Just as we humans digest carbon or food into chunks of sugar that we then use for energy, so too do my bacteria. My bacteria, however, have figured out how to do this digestion process to big, tough, durable PET plastic.

05:03

Now, to do this, my bacteria use a special version of what's called an enzyme. Now, enzymes are simply compounds that exist in all living things. There are many different types of enzymes, but basically, they make processes go forward, such as the digestion of food into energy. For instance, we humans have an enzyme called an amylase that helps us digest complex starches, such as bread, into small chunks of sugar that we can then use for energy. Now, my bacteria have a special enzyme called a lipase that binds to big, tough, durable PET plastic and helps break it into small chunks of sugar that my bacteria can then use for energy. So basically, PET plastic goes from being a big, tough, long-lasting pollutant to a tasty meal for my bacteria. Sounds pretty cool, right?

06:01

And I think, given the current scope of our plastic pollution problem, I think it sounds pretty useful. The statistics I shared with you on just how much plastic waste has accumulated on our planet are daunting. They're scary. And I think they highlight that while reducing, reusing and recycling are important, they alone are not going to be enough to solve this problem. And this is where I think bacteria might be able to help us out.

06:35

But I do understand why the concept of bacterial help might make some people a little nervous. After all, if plastic is everywhere and these bacteria eat plastic, isn't there a risk of these bacteria getting out in the environment and wreaking havoc? Well, the short answer is no, and I'll tell you why. These bacteria are already in the environment. The bacteria in my research are not genetically modified frankenbugs. These are naturally occurring bacteria that have simply adapted to their plastic-polluted environment and evolved the incredibly gnarly ability to eat PET plastic.

07:19

So the process of bacteria eating plastic is actually a natural one. But it's an incredibly slow process. And there remains a lot of work to be done to figure out how to speed up this process to a useful pace. My research is currently looking at ways of doing this through a series of UV, or ultraviolet, pretreatments, which basically means we blast PET plastic with sunlight. We do this because sunlight acts a bit like tenderizer on a steak, turning the big, tough, durable bonds in PET plastic a bit softer and a bit easier for my bacteria to chew on.

08:01

Ultimately, what my research hopes to do is create an industrial-scale contained carbon-free system, similar to a compost heap, where these bacteria can thrive in a contained system, where their sole food source is PET plastic waste. Imagine one day being able to dispose of all of your plastic waste in a bin at the curb that you knew was bound for a dedicated bacteria-powered plastic waste facility. I think with some hard work this is an achievable reality.

08:38

Plastic-eating bacteria is not a cure-all. But given the current statistics, it's clear that we humans, we could use a little help with this problem. Because people, we possess a pressing problem of plastic pollution. And bacteria might be a really important part of the solution.

08:59

Footnotes

00:21

"By 2050, researchers estimate that there will be more plastic in the ocean than fish."

Clarification: It is worth noting that there may be more plastic than fish in the ocean by weight by the year 2050, unless we take significant action to tackle the plastic pollution problem. This prediction comes from a 2016 report from the World Economic Forum, which used Jambeck, et al.'s (2015) predictions about plastic waste for 2025 to make its own projections for 2050. The report's fish projection for 2050 is based on estimates from Jennings et al. (2008) and makes the assumption that fish stock stays constant between 2015 and 2050.

00:28

"Despite our best efforts, only nine percent of all plastic we use winds up being recycled."

"Production, use, and fate of all plastics ever made". Geyer, R., et al., Science Advances, 2017

00:36

"And even worse, plastic is incredibly tough and durable and researchers estimate that it can take anywhere from 500 to 5,000 years to fully break down."

Plastics have been in common use for only about 70 years, and thus we do not yet know how long they take to degrade in the environment. The estimates vary widely, ranging from 50 years to "centuries, if not millennia" and depend on environmental factors. The general consensus seems to be that it takes a long time. Some of the crucial characteristics responsible for plastics' resistance to decomposition are a long-chain polymer structure, a high molecular weight, lack of a favorable functional groups, hydrophobicity and crystallinity. For additional details, see this study by Wilkes, et al. (2012).

01:59

"Researchers estimate that there are roughly five million trillion trillion — that's a five with 30 zeros after it — bacteria on the planet."

For more information on how this estimate was achieved, see:

"Prokaryotes: The unseen majority". Whitman, W. B., et al., PNAS, 1998

02:13

"... humans produce 300 million tons of new plastic each year ..."

Global production of resins and fibers reached 380 million metric tons in 2015. This trend is likely to continue.

02:19

"... our plastic numbers are looking pretty comparable to bacteria's."

Clarification: The number of bacteria on the planet does outweigh the amount of plastic produced to date, but not by that much. The estimated amount of virgin plastics produced to date is about 8.3 billion metric tons, while the number of bacteria on the planet is estimated to be about 70 billion metric tons, which is roughly 8.5 times more than the amount of plastics produced to date. As such, bacterial alternatives to the plastic pollution problem are worth exploring, as there are likely many more bacteria out there capable of degrading plastic.

03:49

"PET plastic is the most widely produced plastic in the world."

Correction: PET is the fourth most widely produced plastic in the world. The most widely produced plastic in the world is polyethylene or PE, which can exist as either high-density polyethylene (HDPE), commonly used in corrosion resistant pipes, milk jugs, juice bottles, or low-density polyethylene (LDPE), used in grocery bags, condiment bottles, cutting boards and more. The second most widely produced plastic is polypropylene or PP, which is used to create items such as food storage bags and plastic jars. And the third is polyvinyl chloride or PVC which is used in pipes, siding material and more.

Plastic is all around us, and there are many different types. Prior research has shown that there are bacteria capable of degrading LDPE and polyurethane or PU, a lining material often found in raincoats. There are bacteria capable of breaking down different types of plastic, and it is important that we continue exploring how to turn these bacteria into a viable solution to combat plastic pollution.

04:00

"... plastic water bottles, of which we humans currently go through at a rate of one million per minute."

"A million bottles a minute: world's plastic binge 'as dangerous as climate change'". Sandra Laville and Matthew Taylor, The Guardian, 2017

04:34

"And using this screen, I was able to find some bacteria that had done just that. These bacteria had figured out how to eat PET plastic."

The genome sequences of the five bacterial strains that I isolated, under the mentorship of microbiologist Jay Mellies, and used in this study — along with evidence to show that they act synergistically to degrade PET plastic — were recently published in the journal Microbiology Resource Announcements.

This research is continuing, and we aim to devise pre-treatment strategies to make the degradation more rapid and to gain a better understanding of the related biological and chemical processes that allow these bacterial species to degrade the plastic cooperatively.

REFERENCES

1. Aotearoa Impacts and Mitigation of Microplastics (AIM²)
   National research programme which aims to determine the impacts of microplastics in New Zealand.
   https://www.esr.cri.nz/expertise/water-environment/microplastics
   They have in the past had presence at public events with organisations like Ecomatters and Seaweek (https://seaweek.org.nz/news/microplastics-nga-korero-webinar-recap)
   You could get in touch with ESR to see if there are any other info sessions coming up.

2. Litter Intelligence
   https://litterintelligence.org/
   National litter monitoring programme, focusing on larger pieces of plastic rubbish from which MPs come from. While it's not directly about MPs, most info that is is based in academic data that is hard for public to access, so Litter Intelligence good inbetween for litter education geared toward schools.

3. Dr Amanda Valois - NZ scientist who has carried out MP research alongside community/volunteer citizen science, could be a good option for giving direction on how the school could get involved with MP monitoring, research, outcomes.
   https://www.nzappa.org/user/avalois/
   amanda.valois@niwa.co.nz

Below are some research papers they could take a look at. Let me know if you're looking for more public access kind of info, like websites.

1. James H. Bridson, Meeta Patel, Anita Lewis, Sally Gaw, Kate Parker,
   Microplastic contamination in Auckland (New Zealand) beach sediments,
   Marine Pollution Bulletin, Volume 151, 2020, 110867, ISSN 0025-326X,
   https://doi.org/10.1016/j.marpolbul.2019.110867.
   (https://www.sciencedirect.com/science/article/pii/S0025326X19310239)
   This study has a couple of sampling sites really close to Rosmini College, so the local data could be really interesting to them. I attach a copy of the article and sample location map in the supporting data doc, since the school might not have access to the paper via ScienceDirect. 

2. Hale, R.C., Seeley, M.E., La Guardia, M.J., Mai, L., Zeng, E.Y., 2020. A Global Perspective on Microplastics. Journal of Geophysical Research: Oceans 125.. https://doi.org/10.1029/2018jc014719
   https://agupubs.onlinelibrary.wiley.com/share/C96PGYU9PJZCHEHWC6I4?target=10.1029/2018JC014719
   Good overview on MPs. 

3. Issac, M.N., Kandasubramanian, B. Effect of microplastics in water and aquatic systems. Environ Sci Pollut Res 28, 19544–19562 (2021). https://doi.org/10.1007/s11356-021-13184-2

4. Padervand, M., Lichtfouse, E., Robert, D. et al. Removal of microplastics from the environment. A review. Environ Chem Lett 18, 807–828 (2020). https://doi.org/10.1007/s10311-020-00983-1

5. Joana Correia Prata, João P. da Costa, Isabel Lopes, Armando C. Duarte, Teresa Rocha-Santos,
   Environmental exposure to microplastics: An overview on possible human health effects, Science of The Total Environment, Volume 702, 2020, 134455, ISSN 0048-9697,
   https://doi.org/10.1016/j.scitotenv.2019.134455.
   (https://www.sciencedirect.com/science/article/pii/S0048969719344468)

ADDITIONAL REFERENCES OCEAN PLastics

"Industrialised Fishing Nations Largely Contribute to Floating Plastic Pollution in the North Pacific Subtropical Gyre," Scientific Reports (2022)

"Extent and Reproduction of Coastal Species on Plastic Debris in the North Pacific Subtropical Gyre," Nature Ecology & Evolution (2023)

"Emergence of a Neopelagic Community Through the Establishment of Coastal Species on the High Seas," Nature Communications (2021) 

"Biodegradation of Polyethylene by the Marine Fungus Parengyodontium Album," Science of the Total Environment (2024)

"A Global Mass Budget for Positively Buoyant Macroplastic Debris in the Ocean," Scientific Reports (2019)

"Global Simulations of Marine Plastic Transport Show Plastic Trapping in Coastal Zones," Environmental Research Letters (2021)

"Global Plastics Outlook: Policy Scenarios to 2060," Organisation for Economic Co-operation and Development (2022)

"Branded 6," Break Free From Plastic (2023)

"Global Producer Responsibility for Plastic Pollution," Science Advances (2024)