Microbes That Eat Plastic

Our Plastic Problem

Humans produce over 380 million tons of plastic every year. Most of it ends up in landfills or the environment, where it can persist for hundreds of years. Traditional plastics are made from petroleum and are designed to last — which is great for durability, but terrible for the planet.

But what if nature found a way to fight back? Enter the plastic-eating microbes.

The Discovery That Changed Everything

In 2016, Japanese scientists made a groundbreaking discovery at a plastic bottle recycling facility in Sakai, Japan. They found a bacterium that had evolved to eat PET (polyethylene terephthalate) — the plastic used in water bottles and polyester clothing.

They named it Ideonella sakaiensis, after the city where it was discovered.

How Does It Work?

I. sakaiensis produces two special enzymes:

• PETase: Breaks down PET plastic into a smaller compound called MHET
• MHETase: Further breaks down MHET into two simple chemicals: terephthalic acid and ethylene glycol

The bacterium can then use these breakdown products as food, converting plastic into biomass and CO₂. A thin film of PET can be completely degraded in about 6 weeks!

Other Plastic-Eating Champions

I. sakaiensis isn't alone. Scientists have discovered other microbes with plastic-eating abilities:

• Pseudomonas species: Some can degrade polyurethane and even break down the toxic additives in plastics
• Aspergillus tubingensis: A fungus found in a Pakistani garbage dump that can degrade polyurethane
• Wax worm gut bacteria: The caterpillars of wax moths can eat polyethylene (plastic bags), and their gut bacteria help with digestion
• Bacillus species: Various strains can break down different types of plastics including polystyrene

Engineering Super Plastic-Eaters

While natural plastic-eating is exciting, it's too slow for industrial use. Scientists are working to supercharge these microbes:

• Enzyme engineering: In 2020, researchers created a "super-enzyme" by combining PETase and MHETase, increasing degradation speed 6x
• Heat tolerance: Modified enzymes that work at higher temperatures, where plastic softens and breaks down faster
• Directed evolution: Using evolution in the lab to create more efficient plastic-eating enzymes

Can This Solve Our Plastic Problem?

Microbial plastic degradation is promising, but there are challenges:

• Speed: Even engineered enzymes are still slow compared to the rate we produce plastic
• Scale: Growing enough bacteria or producing enough enzymes for industrial-scale cleanup is expensive
• Plastic diversity: Different plastics require different enzymes. There's no single solution for all plastics
• Microplastics: Tiny plastic particles scattered in the environment are harder to treat than intact bottles

The Bigger Picture

Plastic-eating microbes are part of a toolkit, not a magic solution. The best approach combines:

• Reducing plastic production and use
• Improving recycling systems
• Developing truly biodegradable alternatives
• Using biological degradation for hard-to-recycle plastics

Evolution in Action

Perhaps the most remarkable thing about I. sakaiensis is that it evolved this ability in just 70 years — the time since PET plastic was invented. Life finds a way, even to exploit an entirely new food source that didn't exist before humans created it.

As we continue to produce plastic waste, evolution will continue to produce organisms that can eat it. The question is whether we can help accelerate this process enough to make a difference — or whether we should simply stop producing so much plastic in the first place.