Replacing Plastic: Can Bacteria Help Us Break The Habit? | KERA News

Replacing Plastic: Can Bacteria Help Us Break The Habit?

Jun 17, 2019
Originally published on June 17, 2019 10:06 am

If civilizations are remembered for what they leave behind, our time might be labeled the Plastic Age. Plastic can endure for centuries. It's everywhere, even in our clothes, from polyester leisure suits to fleece jackets.

A Silicon Valley startup is trying to get the plastic out of clothing and put something else in: biopolymers.

A polymer is a long-chain molecule made of lots of identical units. Polymers are durable and often elastic. Plastic is a polymer made from petroleum products. But biopolymers occur often in nature — cellulose in wood or silk from silkworms — and unlike plastic, they can be broken down into natural materials.

Molly Morse manufactures biopolymers that she hopes will replace some kinds of plastic. She runs a small company called Mango Materials. Mango is her favorite fruit, and she wanted her company to sound different from other tech enterprises in the San Francisco Bay Area. "We're not your typical Silicon Valley startup company," Morse says. "We're manufacturing polymers at a waste-water treatment plant. We're not a bunch of guys in a garage coding."

How did she end up making bioplastic at a sewage treatment plant?

Morse says it started when she was in elementary school. She went to an aquarium and stumbled on an exhibit about plastic trash floating in the ocean. "There was this huge, gigantic-like fish-tank-type structure full of clamshells, like [plastic foam] clamshells from McDonald's," she recalls. "And I was floored ... completely horrified. It changed my life and I was like, that is freaking ridiculous, and I'm going to change it."

She followed through. She went to Stanford University and got a doctorate in environmental engineering. At a scientific conference in 2006, she met another young engineer, Anne Schauer-Gimenez. "I think we were up to like 4 in the morning or something," Schauer-Gimenez says, "just talking about research and how this process works."

The process was how to manufacture biopolymers — using bacteria.

There are certain kinds of bacteria that eat methane. The bacteria use it to make their own biopolymers in their cells, especially if you feed them well. "If we were to get really fat from eating a lot of ice cream or chocolate," Morse explains, "we'd accumulate fat inside our bodies. These bacteria, same thing."

Schauer-Gimenez adds: "To me, microorganisms kind of run the show on planet Earth anyway, so why not let them help us with this process?"

To make biopolymers, the bacteria need lots of food. That's why Mango Materials set up a field site at a sewage treatment plant called Silicon Valley Clean Water in Redwood City, Calif., next to the San Francisco Bay. They got funding from the National Science Foundation, among other backers.

Sewage, or at least the methane gas that sewage emits, is food for bacteria. Treatment plants usually burn off the methane or just vent it into the air. Methane is a potent greenhouse gas that contributes to global warming when it goes into the atmosphere. Mango feeds it to the bacteria.

That's done in a fermenter set up outside, nestled between big steel tanks full of sewage. Engineer Allison Pieja, a third member of the Mango leadership team, shows off their invention. It looks kind of like a big beer keg with pipes sticking in it like intravenous drips. "This is where the magic happens," she says.

Pieja is the bug expert at Mango. "We add the methane and oxygen continuously and kind of drip in our secret sauce based on how the bacteria are growing," she says. The secret sauce is an additive the team developed to keep the process going.

Eventually, when the bacteria are fattened up, the team breaks them open and harvests the biopolymer. They dry it and turn it into pellets.

So far, they've shipped almost 2,000 pounds of their biopolymer to companies interested in using it. Their principal target market is textiles (though they say the biopolymer works for packaging, too). They've produced brightly colored threads that look and feel "plasticky," like polyester maybe. The hope is to weave the biopolymer into clothing to replace plastics in textiles.

A sleeve made from biopolymer for clothing. The Mango team is working with several companies to test how well their biopolymer will work in textiles.
Chris Joyce/NPR

It would be biodegradable clothing, which Schauer-Gimenez says freaks people out. " 'Oh my gosh, you're going to make a swimsuit out of your material? I'm going into the ocean and it's going to biodegrade off my body!' And I'm like, 'No, no, no, no, no, it doesn't quite work like that.' "

To degrade, biopolymers need warm temperatures and the right bacteria around to chew them up, and the process takes weeks or months of constant exposure. Morse acknowledges that if conditions aren't right, though — say in a dry Arizona desert or at the bottom of the ocean — it will take longer.

That's one of the drawbacks of biopolymers so far; some haven't lived up to their promise to biodegrade quickly.

Biology professor John Weinstein at The Citadel in South Carolina put corn-based polymer bags in a wetland and found they degraded even more slowly than regular plastic bags. "You've created a new material," he says of the bioplastic, "but how does it break down? I was surprised."

The federal government and the state of California have penalized companies for selling biodegradable "plastic" that actually takes years to break down.

"Making a statement — 'biodegradable' — that is misleading, especially to the general public," says Ramani Narayan, a chemical engineer at Michigan State University and an expert on bioplastics.

He says it's all about the environmental conditions. And the longer something takes to biodegrade, the longer it's litter. "In that intervening period, it is going to have impacts, and that is what needs to be carefully considered," Narayan says.

Moreover, a big market in biopolymers made from feedstocks such as corn could raise food prices.

Plant-based biopolymers can be composted at an industrial facility that uses high heat and pressure. But Narayan points out that the industry in the U.S. is in its infancy. As for recycling them, he says the recycling industry is already overwhelmed. The Environmental Protection Agency's latest figures, for 2015, show only 9.1% of U.S. plastic waste was recycled. That number is thought to be even lower now that China and other countries have stopped recycling the waste — as little as 2.2% is recycled in the U.S., according to research by engineer Jan Dell, founder of the anti-pollution group The Last Beach Cleanup.

"If we don't have the right waste management infrastructure in play" to recycle new plastic replacements, Narayan says, "then all the things we do at the top end of it is going to be useless."

The team at Mango Materials says their material (a form of polyhydroxyalkanoate, or PHA) is different from most biopolymers and doesn't need to be recycled, but will biodegrade in a month or two in the right conditions. Their products are currently being tested independently to confirm that.

Morse acknowledges there's a lot more to do to pave the way for biopolymers, and she urges people to use less plastic and reuse things instead of throwing them away. But she's following that childhood dream — to find something better than plastic.

"We wouldn't be [doing this] unless we firmly believed that this is a solution to a massive global problem," Morse says.

A problem that won't go away on its own.

Copyright 2019 NPR. To see more, visit https://www.npr.org.

STEVE INSKEEP, HOST:

If a civilization is remembered for what it leaves behind for later eras to see, our time might be known as the plastic age. A Silicon Valley startup is trying to get the plastic out of clothing and put something else in, something that will not last centuries. NPR's Christopher Joyce reports on their experiment in, of all places, a sewage treatment plant.

CHRISTOPHER JOYCE, BYLINE: Molly Morse runs a company in California that makes something called a biopolymers. They're like plastic but made in nature by living things. She calls her company Mango Materials, after her favorite fruit. She says she wanted to sound different.

MOLLY MORSE: We're, if you didn't notice, not your typical Silicon Valley startup company. Like, we're manufacturing polymers at the wastewater treatment plant. We're not a bunch of guys in a garage coding.

JOYCE: So how did this come to be? Well, when Molly Morse was in elementary school, she went to an aquarium and stumbled on an exhibit about plastic trash floating in the ocean.

MORSE: And there was this huge, gigantic, like, fish tank-type structure full of clamshells - like Styrofoam clamshells from McDonald's. And I was floored - like, completely horrified. Like, it changed my life. And I was like, that is freaking ridiculous, and I'm going to change it.

JOYCE: She followed through. Morse went to Stanford University and got a Ph.D. in environmental engineering. At a scientific conference in 2006, she met this young engineer, Anne Schauer-Gimenez.

ANNE SCHAUER-GIMENEZ: I mean, I think we were up till, like, 4 in the morning or something just talking about research and how this process works.

JOYCE: The process was how to make biopolymers. These are malleable materials similar to plastic, but they're made by living things, like cellulose from trees or silk from silkworms. And the bonus is biopolymers can be broken down into natural substances. The two engineers looked for ways to brew up batches of this stuff. They settled on bacteria, special kinds that make their own biopolymers, especially, says Morse, if you overfeed them.

MORSE: If we were to get really fat from eating a lot of ice cream or chocolate, we accumulate fat inside our bodies. These bacteria, same thing.

JOYCE: Schauer-Gimenez went for that.

SCHAUER-GIMENEZ: To me, microorganisms kind of run the show on planet Earth anyway. So why not let them help us with this process?

JOYCE: But the bacteria need lots of food to do that, and that's why they ended up at a sewage treatment plant in Redwood City, Calif. For the bacteria, sewage is food - or at least the methane gas from sewage. Treatment plants usually burn off the methane or just vent it into the air. Here, it's fed to bacteria.

ALLISON PIEJA: So this is where the magic happens in terms of the fermentation.

JOYCE: Engineer Allison Pieja is the third member of the Mango team. She's the bug expert and nurtures the bacteria in a fermenter, kind of like a big beer keg with pipes sticking in it like IV drips.

PIEJA: We add the methane and oxygen continuously and kind of drip in our secret sauce based on how the bacteria are growing.

JOYCE: The secret sauce is an additive that the team developed to keep the process going. Eventually, they bust open the bacteria and harvest the biopolymer. So far, they've shipped 1,700 pounds of that biopolymer to companies to test it in packaging and textiles. In a boardroom at the sewage plant, Morse shows me the results.

MORSE: So this was our fiber grade.

JOYCE: Brightly colored threads, plastic-y (ph) like polyester maybe. The hope is to weave the biopolymer into clothing to replace regular plastics - biodegradable clothing, which, says Schauer-Gimenez, freaks people out.

SCHAUER-GIMENEZ: Oh, my gosh. You're going to make a swimsuit out of your material. I'm going to go in the ocean, and it's going to biodegrade off of my body. And I'm like no, no, no, no, no. It doesn't quite work like that.

JOYCE: Biopolymers need warm temperatures and the right bacteria around to chew them up, and it takes weeks or months of constant exposure. Some kinds of biopolymers, ones made from plant materials like corn, take much longer to degrade, and that's given them a bad reputation.

RAMANI NARAYAN: Making a statement - biodegradable - that is misleading, especially to the general public.

JOYCE: Ramani Narayan is a chemical engineer at Michigan State University. He says the longer something takes to biodegrade, the longer it's litter.

NARAYAN: In that intervening period, it is going to have impacts. And that is what needs to be carefully considered.

JOYCE: Theoretically, biopolymers could be recycled. But Narayan points out that the recycling industry in the U.S. is already overwhelmed. Less than 10% of plastic currently gets recycled. Some research says even less.

NARAYAN: If we don't have the right waste management infrastructure in play, then all the things we do at the top end of it is going to be useless.

JOYCE: The Mango entrepreneurs say their biopolymer will break down faster than others and doesn't need to be recycled. Morse does acknowledge that there's a long way to go to get these biopolymers mainstreamed. In the meantime, she urges people to use less plastic and reuse things instead of throwing them away. But she's following her childhood dream to find something better than plastic.

Christopher Joyce, NPR News. Transcript provided by NPR, Copyright NPR.