Australian researchers reported on June 9, 2022
that darkling beetle larvae can survive solely on Styrofoam, a
promising development for waste management. (photo: Reuters)
Allyson Chiu
/
The Washington Post
17 November 23
One way to help tackle the growing plastic pollution problem could be all around us: microscopic bacteria and fungi.
A growing body of research
has identified a host of microorganisms, some of which can be found in
the bellies of certain larvae and other insects, that contain enzymes
capable of breaking down common types of plastic.
“In no small part because of just how much plastic we’ve polluted
across the planet, in nearly every environmental type, microorganisms
are starting to interact with plastic more,” said Anja Brandon, a
plastics expert with Ocean Conservancy, a nonprofit group. “We’re
finding some that are starting to either evolve and be able to handle
this material or, fortuitously, we’re able to get to actually start
breaking this down.”
Research is still in the early stages, and it remains unclear how
much plastic microorganisms could break down. But given the scale of
plastic pollution, some experts say, it’s necessary to explore a variety
of strategies.
There are more than 170 trillion pieces of plastics in the world’s
oceans — an amount that is doubling about every six years, according to a
major study released in March.
The most obvious way to curb plastic pollution, advocates say, is to
stop producing the material. But that’s challenging for many reasons,
including that it’s difficult to find plastic substitutes that are as cheap and effective.
The world’s nations have moved to create a global treaty on plastic pollution, but they have struggled to agree on how to address the problem.
Bacteria and fungi capable of
breaking down plastics could help support traditional recycling efforts —
if scientists can figure out a way for the microorganisms to do it at
scale.
“To even make a small dent in managing our plastic waste, we really
need to be able to scale up and speed up these systems, which also comes
with its own potential complications,” Brandon said. “Scaling up is
never quite as simple as like, ‘Oh, I’ll just make more of it.’”
Plastic eaters
There is a strong incentive for microorganisms to evolve to eat plastics, said Brandon, who studied biodegradation using mealworms.
Research suggests a number of these organisms appear to have figured
out that plastics could be a valuable food source. In 2015, researchers
from Stanford University found mealworms could live off polystyrene, or what’s widely known as plastic foam. Soon after that, Japanese scientists documented bacteria that could eat plastic bottles. More recently, a team from the University of Texas created
an enzyme that can digest polyethylene terephthalate, a common plastic
resin found in clothes, liquid and food containers. Meanwhile,
researchers in Australia showed that the larvae of a darkling beetle can survive solely on plastic foam.
How these organisms degrade the durable material can lead to
different results. Most bacteria, for instance, secrete certain enzymes
that allow them to break large molecules into smaller ones, Brandon
said. In some cases, these enzymes can chop up a big molecule into its
building blocks. Those simple monomers could be recovered and used to
make new plastic, effectively recycling the material, she said.
It’s also possible for microorganisms to break down plastics into
water, carbon dioxide and organic material known as biomass, other
experts say.
Picky and slow
But many of the known life forms that want to munch on plastics are
picky about what they eat. Most of the microorganisms identified by
researchers will only eat certain kinds of plastic, experts said. That
means if recycling centers want to use this approach, they would still
need to sort trash by material, a complicated process that limits the
kinds of plastics they can recycle today.
“There are too many different types of plastic resins, thousands of
different chemical additives and different colorants,” said Judith Enck,
a former senior Environmental Protection Agency official under
President Barack Obama who now heads the Beyond Plastics advocacy organization. “One size does not fit all.”
These organisms also need time to break down plastics. Brandon’s
research into mealworms that eat polystyrene showed that on average, 100
of the critters could consume 20 to 30 milligrams of plastic per day.
That means it would take 3,000 to 4,000 mealworms to process a single
Styrofoam coffee cup. At this rate, more than a quadrillion mealworms
would be needed to eat just one day’s worth of the world’s plastic
production.
“Even the fastest microorganisms that we found really just pale in
comparison to the amount of plastics we’re making and using in a single
day,” Brandon said.
Researchers at Harvard’s Wyss Institute for Biologically Inspired
Engineering say they’re developing a solution to these obstacles by not
only identifying organisms that can naturally degrade plastic, but also
using genetic engineering to boost their ability to efficiently break
down the material.
The Harvard team is starting by looking for these plastic-eating
microorganisms, said Sukanya Punthambaker, one of the project’s lead
researchers. Then, they plan to isolate the enzymes and work on ways to
speed up their functions.
“It’s a natural solution, so we’re just trying to work with what
nature has already figured out millions of years ago and we’re trying to
expedite that process,” Punthambaker said.
Still at the lab stage
Much of the research into the ability of microorganisms to biodegrade
plastics remains at the laboratory stage. But some experts say if the
approach is scaled up and made to be more efficient, it could have some
use in the real world.
The organisms could help supplement the existing recycling system,
Brandon said, particularly for trash recovered from the environment.
These plastics are often degraded and not suitable to go through most
recycling facilities, so they often end up in landfills.
Still, Brandon and other experts emphasized there is a way to go before these types of solutions can be readily deployed.
Bacteria and enzymes “are incredibly cool and very innovative, and I
can see value for them in the future,” she said. “But in terms of being
the solution or the get out of jail free card from our plastic pollution
crisis, it is simply not the case.”
We have the ways, but do we have the will to save human existence?
