Feeding Frenzy: Larvae’s Digestive Bacteria Render Plastics Biodegradable



Plastic.  It’s everywhere, a pervasive influence in our daily lives.  From grocery bags to water bottles and coffee cups, from product and food packaging to iPhones, plastic is like oxygen to the life of consumerism.  With so much of it used once and tossed in the trash, the waste has built up to frightening proportions, to the point where massive floating landfills cover over three quarters of our oceans’ surface.  (Read more about that HERE.)  The sheer volume we are talking about – not to mention the thousands of years needed for all this plastic to biodegrade– can be cause for despair. And yet... is it possible that there's a solution to be found?

 

Mother Nature may offer us a solution to naturally break down these substances: worms.
 

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More specifically speaking, larvae.  The waxworm (the larval stage of the Indian mealmoth) is happy to dine on polyethylene, which is the type of plastic used to make products such as shower curtains and packaging material.  Their preferred habitat is beehives, where they live as parasites and chew tunnels through the beeswax (which is how they got their name).  However,  it has been found that, in proximity to humans and our inevitable litter, waxworms apparently will make do with plastic.

A second discovery from the
Department of Civil and Environmental Engineering at Stanford presents even more exciting possibilities.  Polystyrene, another type of plastic used in things like foam cups and packing peanuts, has long been considered entirely non-biodegradable.  But the juvenile form of the darkling beetle, better known as the mealworm, has a palate that somehow finds Styrofoam acceptable. 

Mealworms dining on Styrofoam. Image: Wei Mei Mu

Mealworms dining on Styrofoam.
Image: Wei Mei Mu

Incredibly, research has shown that mealworms which were fed a steady diet of polystyrene were no less healthy than their peers who kept a normal diet.  Approximately half of the substance was converted into carbon dioxide, as occurs with regular food, and the rest was excreted within 24 hours as something similar to miniature rabbit pellets.  The study (referenced HERE) considers the droppings biodegradable and completely safe for use as crop soil.

Roadblocks arise on the path to practicality, however.  According to a study published in Environmental Science and Technology, one hundred mealworms consumed an average of only 36 milligrams in a 24-hour time period.  Another study, somewhat more promising, shows that two types of bacteria found in the digestive system of waxworms (Enterobacter asburiae and Bacillus sp. YP1) will continue to munch away on polyethylene, even when displaced from their hosts.  The key then, it seems, is to find a way to exploit the bacteria’s appetite and function on a grand scale.

 


More research is needed,  and further studies are either proposed or already underway to discover whether or not larval digestive microorganisms can also degrade polypropylene (used in textiles), microbeads (used in face wash and toothpaste), and bioplastics.  With more information, scientists may be able to develop stronger enzymes to break down the plastics, and manufacturers could find ways to design materials that are more easily degraded.  Regardless, the current findings, while still in the larval stages themselves, are a promising new tactic in the fight against pollution. 

Visit our sources:

http://phys.org/news/2015-09-plastic-eating-worms-solution-mounting.html
http://www.smithsonianmag.com/smart-news/plastic-loving-bacteria-worms-gut-could-help-break-down-our-pollution-problem-180953528/?no-ist

Author: Justin Haley Philips

The simplest way to combat plastic waste is to minimize consumption in the first place.  

HERE are some steps you can take to reduce your plastic footprint.  Offer your own suggestions in the comments below!