They Eat Plastic For Lunch

They Eat Plastic For Lunch

For years scientists have been on the search for ways to deal with our burgeoning plastic waste burden. The issue of plastic is that it is not really biodegradable. A single piece of plastic can take hundreds to even thousands of years to biodegrade. Plastics are petroleum products that have been synthetically morphed into a product with bonds that organisms are not built to decompose in nature. The fossil fuel oil it is derived from is difficult to break down so instead it pollutes our landfills and leaches toxins into our ecosystems. In efforts to combat this issue, scientists have discovered various bacteria, fungi, and now worms. Past discoveries while novel and beneficial to further studies have not proved to be the savior to our problems. The most promising species, a bacterium called Nocardia asteroides, takes more than six months to obliterate a film of plastic a mere half millimeter thick. Last year, a Japanese team identified a previously unknown bacterium that can degrade PET. And in 2014, Chinese scientists suggested that two species of bacteria from the guts of Indian meal moths, a type of wax worm, can degrade polyethylene (PE)—the world’s most common plastics.

Map from The Wall Street Journal

Just recently Federica Bertocchini, a developmental biologist, discovered a worm that seems to chemically break down plastic. As she was caring for her beehives Bertocchini noticed the waxworms she had put in a plastic bag seemed to have eaten out holes. The type of wax worms Bertocchini had infesting her beehives were a type of moth larvae that feed on beeswax. Waxworms of the moth Galleria mellonella are medium-white caterpillars with black-tipped feet and small, black or brown heads, they live as nest parasites in bee colonies and eat cocoons, pollen, and shed skins of bees, and chew through beeswax, and often bred as fishing bait.

Noticing this strange phenomenon, Bertocchini hypothesized that the same natural process that allows these worms to digest wax may also have gained them to break down this other carbon-carbon bond material known as polyethylene. To test the worms’ capabilities, researchers placed approximately 100 wax worms on plastic bags. Within 40 minutes, the worms had torn sizable holes. After 12 hours, they reduced a single bag by 92 mg, about one-sixth the weight of a typical shopping bag.Though they aren’t sure yet it seems that there is an enzyme in the worms that break down the plastic “perhaps in its salivary glands or a symbiotic bacteria in its gut” according to Bertocchini. According to Eureka Alert, “wax worms wouldn’t normally eat plastic, the researchers suspect that their ability is a byproduct of their natural habits. Wax moths lay their eggs inside beehives. The worms hatch and grow on beeswax, which is composed of a highly diverse mixture of lipid compounds…it’s likely that digesting beeswax and polyethylene involves breaking down similar types of chemical bonds.”

Watch this video from Ruptly to see the worms in action

Though the scientific community is excited to hear and further research any new leads that might solve our world’s biggest issues, there are skeptics of the reliability of using wax worms and other organisms to solve our plastic debacle. One question raised is the composition of the wax worm feces after digesting plastics. Ed Yong at The Atlantic says “if these [wax worm feces] turn out to be toxic, then there will be little point in pursuing the matter”. Another concern is the relationship between wax worms and bee populations. Philip Ball at The Guardian worries that “with bee populations already under severe stress from pesticides, habitat loss and predators, we might want to think twice about breeding one of their common airborne enemies in huge numbers – even if the intention was to somehow keep them in plastics-processing centers.” Ball also states that “you’d need an awful lot of them to make a significant dent in the plastic waste problem”. Marine biologist Tracy Mincer of the Woods Hole Oceanographic Institute in Massachusetts told Huffington Post that instead of focusing on worms, efforts should focus on decreasing plastic production and increasing recycling. “In my opinion, although this is an amazing natural history story and wonderful academic exercise, it is not a solution for disposing of polyethylene, as this is throwing away money.”
It is important to note that researchers handling this new discovery have not claimed breeding wax worms for biodegrading plastics as their goal. Rather, scientists will begin to isolate individual elements within extracts from the worms, in an attempt to narrow down the chemical breaking the plastic’s bonds. If they are able to isolate that enzyme, then it might be possible to obtain the gene governing it and to insert that gene into a bacteria, which could be easier than cultivating the worms according to researcher Christopher J. Howe.

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