09:21
TED2013

Two young scientists break down plastics with bacteria

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Once it's created, plastic (almost) never dies. While in 12th grade Miranda Wang and Jeanny Yao went in search of a new bacteria to biodegrade plastic -- specifically by breaking down phthalates, a harmful plasticizer. They found an answer surprisingly close to home.

- Science fair winners
Miranda Wang and Jeanny Yao have identified a new bacteria that breaks down nasty compounds called phthalates, common to flexible plastics and linked to health problems. And they’re still teenagers. Full bio

Miranda Wang: We're here to talk about accidents.
00:12
How do you feel about accidents?
00:15
When we think about accidents,
00:17
we usually consider them to be harmful,
00:19
unfortunate or even dangerous, and they certainly can be.
00:21
But are they always that bad?
00:25
The discovery that had led to penicillin, for example,
00:28
is one of the most fortunate accidents of all time.
00:30
Without biologist Alexander Fleming's moldy accident,
00:34
caused by a neglected workstation,
00:37
we wouldn't be able to fight off so many bacterial infections.
00:39
Jeanny Yao: Miranda and I are here today
00:44
because we'd like to share how our accidents
00:46
have led to discoveries.
00:48
In 2011, we visited the Vancouver Waste Transfer Station
00:50
and saw an enormous pit of plastic waste.
00:54
We realized that when plastics get to the dump,
00:57
it's difficult to sort them because they have similar densities,
01:00
and when they're mixed with organic matter
01:03
and construction debris, it's truly impossible
01:05
to pick them out and environmentally eliminate them.
01:07
MW: However, plastics are useful
01:10
because they're durable, flexible,
01:13
and can be easily molded into so many useful shapes.
01:15
The downside of this convenience
01:18
is that there's a high cost to this.
01:20
Plastics cause serious problems, such as
01:23
the destruction of ecosystems,
01:25
the pollution of natural resources,
01:27
and the reduction of available land space.
01:29
This picture you see here is the Great Pacific Gyre.
01:31
When you think about plastic pollution
01:34
and the marine environment,
01:36
we think about the Great Pacific Gyre,
01:38
which is supposed to be a floating island of plastic waste.
01:39
But that's no longer an accurate depiction
01:43
of plastic pollution in the marine environment.
01:45
Right now, the ocean is actually a soup of plastic debris,
01:48
and there's nowhere you can go in the ocean
01:52
where you wouldn't be able to find plastic particles.
01:54
JY: In a plastic-dependent society,
01:57
cutting down production is a good goal, but it's not enough.
02:00
And what about the waste that's already been produced?
02:03
Plastics take hundreds to thousands of years to biodegrade.
02:06
So we thought, you know what?
02:10
Instead of waiting for that garbage to sit there and pile up,
02:11
let's find a way to break them down
02:15
with bacteria.
02:17
Sounds cool, right?
02:19
Audience: Yeah. JY: Thank you.
02:21
But we had a problem.
02:22
You see, plastics have very complex structures
02:24
and are difficult to biodegrade.
02:27
Anyhow, we were curious and hopeful
02:30
and still wanted to give it a go.
02:32
MW: With this idea in mind, Jeanny and I read through
02:33
some hundreds of scientific articles on the Internet,
02:36
and we drafted a research proposal
02:38
in the beginning of our grade 12 year.
02:40
We aimed to find bacteria from our local Fraser River
02:43
that can degrade a harmful plasticizer called phthalates.
02:46
Phthalates are additives used in everyday plastic products
02:50
to increase their flexibility, durability and transparency.
02:52
Although they're part of the plastic,
02:57
they're not covalently bonded to the plastic backbone.
02:59
As a result, they easily escape into our environment.
03:01
Not only do phthalates pollute our environment,
03:04
but they also pollute our bodies.
03:07
To make the matter worse, phthalates are found in products
03:09
to which we have a high exposure, such as babies' toys,
03:12
beverage containers, cosmetics, and even food wraps.
03:16
Phthalates are horrible because
03:20
they're so easily taken into our bodies.
03:22
They can be absorbed by skin contact, ingested, and inhaled.
03:24
JY: Every year, at least 470 million pounds of phthalates
03:29
contaminate our air, water and soil.
03:32
The Environmental Protection Agency
03:36
even classified this group as a top-priority pollutant
03:37
because it's been shown to cause cancer and birth defects
03:40
by acting as a hormone disruptor.
03:44
We read that each year, the Vancouver municipal government
03:46
monitors phthalate concentration levels in rivers
03:49
to assess their safety.
03:51
So we figured, if there are places along our Fraser River
03:53
that are contaminated with phthalates,
03:56
and if there are bacteria that are able to live in these areas,
03:58
then perhaps, perhaps these bacteria could have evolved
04:01
to break down phthalates.
04:05
MW: So we presented this good idea
04:07
to Dr. Lindsay Eltis at the University of British Columbia,
04:10
and surprisingly, he actually took us into his lab
04:13
and asked his graduate students Adam and James to help us.
04:16
Little did we know at that time
04:20
that a trip to the dump and some research on the Internet
04:22
and plucking up the courage to act upon inspiration
04:25
would take us on a life-changing journey
04:28
of accidents and discoveries.
04:30
JY: The first step in our project
04:33
was to collect soil samples from three different sites
04:35
along the Fraser River.
04:37
Out of thousands of bacteria, we wanted to find ones
04:39
that could break down phthalates,
04:42
so we enriched our cultures with phthalates
04:43
as the only carbon source.
04:45
This implied that, if anything grew in our cultures,
04:47
then they must be able to live off of phthalates.
04:49
Everything went well from there,
04:52
and we became amazing scientists. (Laughter)
04:54
MW: Um ... uh, Jeanny. JY: I'm just joking.
04:57
MW: Okay. Well, it was partially my fault.
05:00
You see, I accidentally cracked the flask
05:02
that had contained our third enrichment culture,
05:05
and as a result, we had to wipe down the incubator room
05:07
with bleach and ethanol twice.
05:10
And this is only one of the examples of the many accidents
05:12
that happened during our experimentation.
05:15
But this mistake turned out to be rather serendipitous.
05:17
We noticed that the unharmed cultures
05:20
came from places of opposite contamination levels,
05:23
so this mistake actually led us to think that
05:26
perhaps we can compare
05:28
the different degradative potentials of bacteria
05:30
from sites of opposite contamination levels.
05:33
JY: Now that we grew the bacteria,
05:37
we wanted to isolate strains by streaking onto mediate plates,
05:39
because we thought that would be
05:42
less accident-prone, but we were wrong again.
05:44
We poked holes in our agar while streaking
05:47
and contaminated some samples and funghi.
05:51
As a result, we had to streak and restreak several times.
05:53
Then we monitored phthalate utilization
05:56
and bacterial growth,
05:59
and found that they shared an inverse correlation,
06:01
so as bacterial populations increased,
06:03
phthalate concentrations decreased.
06:06
This means that our bacteria were actually living off of phthalates.
06:08
MW: So now that we found bacteria that could break down phthalates,
06:12
we wondered what these bacteria were.
06:15
So Jeanny and I took three of our most efficient strains
06:17
and then performed gene amplification sequencing on them
06:20
and matched our data with an online comprehensive database.
06:23
We were happy to see that,
06:26
although our three strains had been previously identified bacteria,
06:27
two of them were not previously associated
06:31
with phthalate degradation, so this was actually a novel discovery.
06:34
JY: To better understand how this biodegradation works,
06:38
we wanted to verify the catabolic pathways of our three strains.
06:42
To do this, we extracted enzymes from our bacteria
06:46
and reacted with an intermediate of phthalic acid.
06:49
MW: We monitored this experiment with spectrophotometry
06:52
and obtained this beautiful graph.
06:55
This graph shows that our bacteria really do have
06:58
a genetic pathway to biodegrade phthalates.
07:00
Our bacteria can transform phthalates, which is a harmful toxin,
07:03
into end products such as carbon dioxide, water
07:06
and alcohol.
07:09
I know some of you in the crowd are thinking,
07:10
well, carbon dioxide is horrible, it's a greenhouse gas.
07:11
But if our bacteria did not evolve to break down phthalates,
07:15
they would have used some other kind of carbon source,
07:18
and aerobic respiration would have led it
07:21
to have end products such as carbon dioxide anyway.
07:23
We were also interested to see that,
07:26
although we've obtained greater diversity
07:28
of bacteria biodegraders from the bird habitat site,
07:31
we obtained the most efficient degraders from the landfill site.
07:33
So this fully shows that nature evolves
07:37
through natural selection.
07:39
JY: So Miranda and I shared this research
07:42
at the Sanofi BioGENEius Challenge competition and were recognized
07:44
with the greatest commercialization potential.
07:47
Although we're not the first ones to find bacteria
07:50
that can break down phthalates,
07:53
we were the first ones to look into our local river
07:54
and find a possible solution to a local problem.
07:56
We have not only shown that bacteria
08:00
can be the solution to plastic pollution, but also that
08:03
being open to uncertain outcomes and taking risks
08:06
create opportunities for unexpected discoveries.
08:09
Throughout this journey, we have also discovered our passion for science,
08:13
and are currently continuing research
08:16
on other fossil fuel chemicals in university.
08:18
We hope that in the near future,
08:21
we'll be able to create model organisms
08:23
that can break down not only phthalates
08:25
but a wide variety of different contaminants.
08:27
We can apply this to wastewater treatment plants
08:31
to clean up our rivers
08:34
and other natural resources.
08:35
And perhaps one day we'll be able to tackle
08:37
the problem of solid plastic waste.
08:40
MW: I think our journey has truly transformed
08:44
our view of microorganisms,
08:46
and Jeanny and I have shown that
08:48
even mistakes can lead to discoveries.
08:50
Einstein once said,
08:52
"You can't solve problems by using the same kind
08:53
of thinking you used when you created them."
08:56
If we're making plastic synthetically, then we think
08:59
the solution would be to break them down biochemically.
09:02
Thank you. JY: Thank you.
09:06
(Applause)
09:08

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About the Speaker:

Miranda Wang and Jeanny Yao - Science fair winners
Miranda Wang and Jeanny Yao have identified a new bacteria that breaks down nasty compounds called phthalates, common to flexible plastics and linked to health problems. And they’re still teenagers.

Why you should listen

After a visit to a plastic-filled waste transfer station last year, students Miranda Wang and Jeanny Yao learned that much of the plastic in trash may not degrade for 5,000 years. Synthesized into plastics are phthalates, compounds that make shower curtain liners, food wraps and other products bendable but may also adversely impact human reproductive development and health.  As plastics slowly break down, these phthalates would leach into the surrounding environment.

So, the two young scientists tackled the problem and ultimately discovered strains of bacteria that have the potential to naturally degrade phthalates. Their work earned a regional first place in British Columbia for the 2012 Sanofi BioGENEius Challenge Canada, as well as a special award for the most commercial potential at the contest’s finals.

More profile about the speaker
Miranda Wang and Jeanny Yao | Speaker | TED.com