Mealworms on a Piece of Potato
Credit: BenGrantham (ijammin on flickr) / Licensed under Creative Commons Attribution 2.0 Generic

On September 29th, 2015, a Stanford News post by Rob Jordan announced an incredible discovery: Stanford engineers and Chinese researchers have found that common mealworms can safely consume some types of plastic.

In the study co-authored by Wei-Min Wu, Stanford's senior research engineer in the Department of Civil and Environmental Engineering titled Biodegradation and Mineralization of Polystyrene by Plastic-Eating Mealworms: Part 1. Chemical and Physical Characterization and Isotopic Tests published on September 21st, 2015, it found: 

  • Mealworms (Tenebrio molitor Linnaeus aka yellow mealworm) fed Styrofoam (a polystyrene product) as their sole diet, lived as well as those fed with a normal diet (bran) over a period of 1 month. 
  • Within a 16 day test period, 47.7% of the ingested Styrofoam carbon was converted into carbon dioxide (CO2) and the residue (about 49.2%) was excreted (egested as fecula).

Plastic and Garbage on Pantai Liang, Pulau Bunaken, SulawesiFabio Achilli on flickr / CC-by-2.0Apparently, the mealworms' guts contain microorganisms that biodegrade the plastic which surprised researchers.

Dr. Wu told Stanford News:

"Our findings have opened a new door to solve the global plastic pollution problem."

Likewise, Craig Criddle, professor of civil and environmental engineering who supervises plastics research by Wu and others at Stanford, remarked:

"There's a possibility of really important research coming out of bizarre places. Sometimes, science surprises us. This is a shock."

Up next is a short 53-second YouTube video by NewsBeat Social published on September 30th, 2015.

Mealworms Could Offer Plastic Pollution Solution

Published September 30th, 2015 by NewsBeat Social

The Research Method and Implications

According to Dr. Wu, the mealworms converted approximately half of the Styrofoam into carbon dioxide – which is no different from any food source. And within a day (24 hours), they excreted the rest of the plastic "as biodegraded fragments" which resembled small rabbit droppings.

This Styrofoam waste from the mealworms "appeared to be safe" to use for crops to grow food. It could even be used as soil, presumably.

Previous research by other scientists and Dr. Wu found that waxworms (the larvae of Indian mealmoths), have microorganisms in their guts that can biodegrade polyethylene. Polyethylene is the most common plastic. It's used in the manufacture of a multitude of products including plastic bags and plastic bottles.

And according to a news release on January 28th, 2015 by Worldwatch Institute titled Global Plastic Production Rises, Recycling Lags, between 22 percent and 43 percent of the plastic used worldwide is disposed of in landfills. And about 10 to 20 million tons of plastic end up in the oceans each year.

Obviously both discoveries are hugely significant. And yet Styrofoam was believed to be non-biodegradable and "more problematic for the environment."

Styrofoam MountainDavid Gilford on flickr / CC-by-2.0

In my Environment911 article Save the Planet and Solve Poverty: Demand Shrilk or Recycled Ocean Plastic, I delved into how disturbing our global plastic problem has become. And I was excited by the invention of shrilk by Harvard scientists Javier G. Fernandez and Donald Ingber.

Shrilk is made of discarded shrimp shells and silk protein from the domestic silkworm.

Yet the methods used to obtain shrimp disturbed me. In my article New Caledonia Creates the Largest Protected Natural Area in the World, I discuss how deep sea bottom trawling is destroying ocean life. In fact, shrimp trawling is responsible for a whopping third of the world's bycatch, yet only comprises two percent of all seafood.

And Paw Mane Fin's own Emily Heeb reported that a New Study Finds Nearly Every Seabird on Earth is Eating Plastic on September 15th, 2015. Which raises the question: just how safe is it for other species to consume mealworms that only eat Styrofoam?

Or for us? What about food grown in fields of mealworm excrement from Styrofoam-eating worms?

Ongoing Studies and Further Research

Fortunately, Criddle is leading research and collaborating with Jun Yang and other researchers from Beihang University in China.

They plan to study whether the microorganisms inside the guts of mealworms (and other insects) can biodegrade the following:

  • Polypropylene (used in textiles and even automotive parts)
  • Microbeads (used in exfoliants in soaps and facial scrubs)
  • Bioplastics (made from sources such as biogas methane or corn)

I was relieved to learn these researchers will explore what happens when these materials are consumed by small animals (which are eaten by other animals) along the food chain.

But as noted in Emily Heeb's article (and numerous other publications), plastic in our oceans is a huge problem. And it appears that Criddle has also addressed this issue. In Stanford News, he mentioned:

"Another area of research could involve searching for a marine equivalent of the mealworm to digest plastics. Plastic waste is a particular concern in the ocean, where it fouls habitat and kills countless seabirds, fish, turtles and other marine life."

Once more research can flesh out which conditions and enzymes break down polymers, scientists may be able to engineer more powerful enzymes to help decompose plastic (safely).

One day, polymers could be designed that do not end up in the food chain or the environment.

This is truly exciting news. I just hope it's not too late for our planet and everything that lives in it.

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