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Mealworms’ gut bacteria possible plastic pollution reduction solution, specialist says

Olivier Rey / Red Dirt Report
Wu talking at the conference on Jan. 4 at the University of Oklahoma.
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NORMAN, Okla. – Wei-min Wu, a specialist on environmental biotechnology at Stanford University talked on “Microplastic pollution and recent progress in biodegradation of petroleum-based plastics” on Jan. 4 at the University of Oklahoma.

Wu said recent studies showed bacteria contained in mealworms’ gut are able to eat and degrade polystyrene and polyethylene foams, providing a possible solution to the reduction of the plastics pollution.

Presentation of plastic microbeads. (Olivier Rey / Red Dirt Report)

Today most of the microplastics (size less than 1 mm) wastes are coming from China, Europe, and America, polluting rivers, oceans, and groundwater. Wu said microplastics are essentially composed of microbeads (tiny plastic balls) that can be found in personal care products such as toothpaste. He added microplastics cannot be removed by existing treatment water plans, only microfiltration works.

Representation of the cycle of microplastics pollution. (Olivier Rey / Red Dirt Report)

Wu said the result is a contamination of the fish, mollusks, plankton and even sea salts that can be found in every supermarket. Wu believes plastics contamination can be reduced by minimizing the use of plastics and increasing recycling.

He said the reason why microplastics are essentially composed of polystyrene and polyethylene is due to their low densities (lower than water) that make it easy to travel and difficult to recycle (high cost). Only nine percent of plastics are recycled in the U.S. And for the plastics lost in nature, studies showed it could take centuries before a complete degradation.

Yellow mealworm presentation. (Olivier Rey / Red Dirt Report)

It is in this context that the Yellow mealworm, mainly found in Europe and North America, can play an important role. Rich in protein, the Yellow mealworm is commonly used to feed animals, more recently some restaurants and start-ups started to propose the mealworm for human consumption.

However, besides these common uses, Wu said it has been observed that mealworms are able to eat plastics, especially Styrofoam, a kind of expanded polystyrene.

“They are not only eating Styrofoam plastics, but also degrading it,” Wu said.

Studies showed mealworms can eat up to 50 percent of the Styrofoam in over two weeks, with up to 70 percent of the plastic has been degraded. Wu said it takes from five to 15 hours to digest plastics for a mealworm adding, “It is pretty fast.”

The mealworm is more efficient when the temperature reaches 77° F but has a better chance to survive in lower temperatures.

“They don’t like high temperatures,” Wu said, noting mealworms eating Styrofoam are able to complete their life cycle, showing that Styrofoam is not harmful to them.

Wu also said the assimilation and degradation of the plastic are made possible by several types of bacteria contained in the mealworm’s gut. One of them, the Exiguobacterium is particularly efficient. However, studies showed that experiment of the bacteria degrading Styrofoam out of the mealworm’s gut had only eaten 7.8 percent of the Styrofoam after two months, far from the performance observed directly with the mealworm.

“It will need time to improve the technique,” Wu said.

Besides the mealworm, Wu said other bacteria contained in insects, such as the waxworms and cockroaches could play an important role in the biodegradation of petroleum plastic in the next decades. At the date, Wu said there is no industrial process to try to take advantage of the mealworm efficacy for eating and degrading plastics.

Wu told Red Dirt Report that mealworms could be able to directly eat microbeads, but has not published the results of his study yet.

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Olivier Rey

Olivier has traveled in 20 countries on six continents before landing in Norman. Native French...

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