A caterpillar commercially bred for use as fishing bait was found to have the ability to biodegrade polyethylene, the most commonly used plastic in manufacturing shopping bags.
About 80 million tons of polyethylene are produced annually primarily for use in packaging. Reliance on this plastic raises concern since it will take about 100 years for a low-density polyethylene bag to degrade completely. Denser plastics would take as long as 400 years to disintegrate.
A researcher, who also happens to be an amateur beekeeper, accidentally discovered that the wax worm, the larvae of the common insect called Galleria mellonella, or greater wax moth, has the potential to solve current problems with plastic waste, particularly polyethylene.
Further investigation revealed it was not the caterpillar's manner of chewing that degrades the plastic. The creature actually produces something that can break down the polymer chains in polyethylene plastic.
"Perhaps in its salivary glands or a symbiotic bacteria in its gut. The next steps for us will be to try and identify the molecular processes in this reaction and see if we can isolate the enzyme responsible," said study researcher Paolo Bombelli, of the University of Cambridge. "This discovery could be an important tool for helping to get rid of the polyethylene plastic waste accumulated in landfill sites and oceans."
Plastic pollution is a growing problem with at least 275 million tons of this waste being produced annually by 192 nations worldwide. Of these, nearly 8 million tons are washed up into the ocean.
The plastic debris in the waters are being blamed for the death of many animals including those that mistake the colorful plastic as food and those caught in plastic fishing lines.
The wax worm may offer a promising solution that can help with plastic waste problem but other organisms have also been identified in the past to have the potentials for degrading plastic.
Last year, Japanese scientists reported of a new species of bacteria that eats the plastic used in most disposable water bottles. The plastic called polyethylene terephthalate, or PET, can also be found in frozen-dinner trays, blister packaging and polyester clothing.
The bacteria species known as Ideonella sakaiensis was found to use two enzymes to break down plastic. Researchers said that a community of Ideonella sakaiensis can break down a thin film of PET over a period of six weeks given a stable temperature of 86 degrees Fahrenheit.
"When grown on PET, this strain produces two enzymes capable of hydrolyzing PET and the reaction intermediate, mono(2-hydroxyethyl) terephthalic acid. Both enzymes are required to enzymatically convert PET efficiently into its two environmentally benign monomers, terephthalic acid and ethylene glycol," researcher Shosuke Yoshida of Kyoto Institute of Technology, and colleagues described the bacteria in the journal Science.
Mushroom That Can Break Down Plastic
In 2012, researchers from Yale University discovered a variety of mushroom called Pestalotiopsis microspora that can also break down polyurethane. Two years after its discovery, a system was developed that aims to make it possible to eat these plastic-digesting fungi.