Our planet is cluttered with an egregious amount of a miracle substance known as plastic. Here are a few bitter truths of this issue:
- Most plastic has not even been around longer than a century, but it can take up to 450 years to fully biodegrade.
- As much as 311 metric tons of plastic was produced in 2014, 80 percent of which was for single-use packaging, so most of the plastic we produce goes straight to the dump or into the ocean.
- Scientists estimate that by 2050, the aggregate volume of plastic in the oceans will be greater than that of fish.
You may be wondering where all of this plastic goes. Plastic dumped into the ocean generally accumulates in gyres such as a Texas-sized cluster of floating debris known as the “Great Pacific Garbage Patch.” At sea, plastics gradually break down into smaller and smaller bits, but they don’t fully disappear. They diminish to the size of microscopic filaments. In this form, plastic enters the bottom of the food chain.
Organisms of all sizes are tempted by plastic and they mistake it for food. The shape, size, taste, and even smell of plastic is often deceptively similar to the regular food sources of many animals. At least 267 marine species have been observed eating plastic. Scientists still don’t know exactly how internal plastic accumulation affects the physical or behavioral patterns of different species.
Fortunately, a few organisms that can actually digest plastic have been discovered. Certain worms, fungi, and microbes can transform it into biodegradable matter. These organisms tend to have much slower rates of consumption than, say, a sea-faring albatross that collects plastic in its stomach. Still, scientists hope that by researching the enzymes found within these organisms, they can discover ways to speed up plastic decomposition.
10. Seabirds drawn by scent
When seabirds catch a whiff of the plastic floating in the sea, it lures them. Researchers have found that ocean plastic tends to smell like a compound called dimethyl sulfide (DMS). Though not attractive to humans, it has the same scent-signature as algae. Scientists just don’t know why. Maybe it’s like tupperware containing leftovers in the fridge that never loses its meatball scent and the nearby smells of the ocean just cling to the plastic debris. Albatross, a seabird known for its majestic size, are probably the most notorious plastic eaters. They feed indiscriminately by skimming the surface of the water, collecting plastic shards in their stomachs. Photographer Chris Jordan has captured the overburdened stomachs of their carcasses on film and he’s preparing a documentary to highlight the problem. However, the seabirds with the highest appetite for plastic are parakeet auklets from Alaska. The phenomenon of birds eating plastic is obviously troublesome because of its prevalence. As of 1980, scientists had already found plastic in the stomachs of 80 percent of seabirds. While this is not the only threat to seabirds, it may have contributed to their sharp population decline by 67 percent from 1950 to 2010.
9. Barnacles: in one end, out the other
Barnacles attach their craggy shells firmly to the sides of boats, piers, and other man-made structures. Plastic floating in the ocean is no exception. In 2009, the researcher Miriam Goldstein of the Scripps Institution of Oceanography in California traveled to the North Pacific Subtropical Gyre, a more elegant name for the “Great Pacific Garbage Patch.” There, she observed the species growing in the plastic debris. She found an abundance of gooseneck barnacles sucking in and eventually pooping out plastic pieces. One third of the barnacles she had collected contained plastic pieces, though because the plastic could go in one end and out the other, an even higher percentage might be eating plastic. At the time Goldstein discovered the barnacles eating plastic, only three other types of invertebrates were known to eat plastic: sand fleas, the Norway lobster, and flying squid.
8. Microscopic Zooplankton
By now, microplastics that can only be viewed through a microscope are prevalent throughout the natural environment. They are created by the breakdown of plastic garbage in the ocean and by washing polyester clothing. Microplastics have been found everywhere from human drinking water sources to the deepest reaches of the ocean. Zooplankton, a microscopic crustacean, ingests any object the size of its regular food. In a recent study, over a third of the observed copepods, a kind of zooplankton living in the Northeast Pacific Ocean, had ingested microplastic. These creatures, invisible to the eye, are eaten by krill, shrimp, and small fish, which are then eaten by larger predators. The baffling phenomenon of microplastics entering the food chain has scientists wondering how these microplastics will affect organisms as they work their way into the bodies of all kinds of animals including humans.
7. Coral: Picky Plastic Eaters
Perhaps you’ve started to see a trend in this list: that sea creatures that eat whatever’s in sight are the most impacted by plastic. For coral, though, it’s a matter of taste. Coral lack eyes, so they’re not attracted to the bright color of plastic. Instead, they show a striking preference for the flavor of clean plastic. They will eat clean plastic three times as much as plastic covered in bacteria. This finding was the result of recent research published by Austin S. Allen, a PhD student at Duke University’s Nicholas School of the Environment. Beyond the criterion of cleanliness, coral consume pretty much any kind of microplastic, including polystyrene (styrofoam) and polyethylene (a versatile plastic). However, once they’ve welcomed the plastic into their stomachs, coral have a hard time pushing it out, unlike barnacles. This means that plastic can block the intestinal tracts and lower the energy of coral. Worst of all for these sea creatures craving a tasty morsel of food, eating plastic may leave coral with a false sense of fullness. However, plastic may do even more than stop up the digestive system. It could also leach industrial chemicals into the bodies of the glorious red reef that laces the ocean floor. Some researchers speculate that it could even affect their sexual preferences. More research is yet to be done.
6. Edible Plastic-eating Mushrooms
Fortunately, not all organisms are just trapping plastic in their stomachs. As promised, I’ll describe a few that can digest the stubborn material. The first of these is a commonly known species that we can find in a grocery store: an oyster mushroom. Not only can it eat plastic, but we can also safely eat it. Austrian designer Katharina Unger has created a prototype for an in home growth chamber known as a “Fungi Mutarium” for feeding plastic to edible mushrooms. The design itself looks like something from a science fiction movie set. Inside the chamber are pods containing agar, a seaweed-based gelatin, and bits of plastic for the mushrooms to feed on. After placing the diluted mycelia, a network of tiny root-like filaments in the pods, the mushrooms gradually balloon into edible morsels. The plastic must first undergo UV treatment to start the process of decay, but after that, a small piece of plastic can be fully consumed by the fungus in a couple of months. The caveat about this design is that so far, it is only suitable for biodegradable plastic. However, researchers hope to adjust growth conditions to enable the fungus to consume non-biodegradable plastic in the future.
5. A Discovery in the Amazon
Students discovered a mushroom that can live exclusively on polyurethane hiding in the thick foliage of the Amazonian rainforest. Led by their professor Scott Strobel, the students of Yale University’s Department of Molecular Biophysics and Biochemistry took an annual research trip in 2011 that enabled them to identify this unique trait of the fungus, Pestalotiopsis microspora. Though the fungus had been previously spotted in Buenos Aires and Japan, no one had realized its capabilities. Not only can the fungus survive solely by eating plastic, it does not require oxygen to do so, meaning it can potentially thrive underneath the waste accumulating in landfills. Furthermore, polyurethane is a highly common and versatile form of plastic used to make products such as synthetic leather, tires, hoses and condoms. Because the fungus can break down its molecular bonds, researchers are now speculating about new possibilities for approaching the plastic waste problem with bioremediation. It has also inspired many scientists to search for similar species.
4. Landfill Fungus of Pakistan
Researchers in Pakistan wasted no time in going to the potential source of more plastic-eating organisms: the rotting ecosystem of a landfill. Thanks to their intuitions, they discovered a soil fungus that feeds on plastic in a dump outside of Islamabad. The species name of the fungus is Aspergillus tubingensis and like Pestalotiopsis microspora, it also feeds on polyurethane. The fungus “treats” the plastic in multiple stages to break down its complex polymers. First, it uses enzymes, and then its mycelia proceed to finish off what’s left of the material. The researchers tried different environments for the fungus to degrade the plastic including on an agar plate, in liquid, and buried in soil. The agar plate provided the most successful results. However, the researchers also found that as the fungus eats the plastic, it has an unwanted side effect. It also releases some greenhouse gas emissions. Nevertheless, by observing the landfill for its biological features, the researchers have opened a window future possibilities.
3. Styrofoam-eating Mealworms
Tiny wriggling larvae prevalent throughout the world have kept their useful talent’s secret until recently. Chinese scientists from the Department of Environmental Science and Technology at the Jun Yangfrom Beihang University discovered that mealworms, the larvae of the darkling beetle, appeared to be eating polystyrene, which is used to manufacture Styrofoam. At first, they weren’t sure if the mealworms were merely chewing up the material or if they were actually digesting it. It turns out the little larvae had converted the material to carbon dioxide, worm biomass and biodegradable waste. Fortunately, they excrete nothing toxic or harmful, and the resulting material seems safe for plant soil. The rate that they eat the polystyrene, though appears underwhelming on paper. Every day, 100 mealworms consumed the weight of a pill (34-39 milligrams) of Styrofoam. However, the scientists really wanted to know what internal chemicals were enabling this fascinating digestive feat, so they used different feed samples to isolate the enzyme causing the decomposition: Exiguobacterium sp. strain YT2. Furthermore, none of the mealworms eating styrofoam rather than bran appeared to suffer any health damage from the experiment.
2. Pesky Waxworms Eat Shopping Bags
A pest to beekeepers may be an ally for waste management. Wax worms ravage the beeswax of honeycombs and they later metamorphose into wax moths, common throughout Eurasia. As it turns out, they are also capable of eating and digesting plastic shopping bags. This discovery was recently made by a scientist and amateur beekeeper who tried to capture the pests in a plastic bag. She was surprised to find that they had munched their way out of captivity. With additional testing, she discovered that the worm had indeed digested the plastic, which has a similar chemical structure to the beeswax they normally eat. The excreted substance their bodies produce after eating plastic is called ethylene glycol. It is a moderately toxic chemical used in antifreeze. In 12 hours, 100 worms ate 92mg of polyetheylene, the weight of three pills. The scientists researching these drab, previously unwanted worms, seek to isolate the enzymes waxworms produce to digest complex polymers.
1. Japanese Bacteria Breaking Down Plastic Bottles
In the world of plastics, each polymer presents its own molecular puzzle for biodegradability. That’s why finding organisms capable of feasting on different types of plastic excites scientists. Recently scientists in Japan have discovered a strain of bacteria capable of decomposing the plastic used to make water bottles, peanut butter jars, and other containers. They found it growing at a recycling plant where plastic already gets diminished and transformed for alternate use. This type of plastic is known as polyethylene terepthalate, or PET, depicted by the number 1 in the triangle label. The bacteria Ideonella sakaiensis performs a dual-stage process, secreting two different enzymes in sequence to gradually break down the polymer. The rate is painfully slow, rendering it useless for any industrial application. Yet, the bacteria successfully broke down a thin film of PET over the course of six weeks. So far, the bacteria can only break down amorphous PET, rather than the crystalline PET used in products, so more testing and experimentation lies ahead.
Whether these plastic eating organisms shall become useful still remains uncertain. The dilemma of plastic accumulation is so great that replacing it with biodegradable materials seems to be the most sensible solution. Yet, these plastic-eating bacteria highlight the fact that the long wait-time for plastics to decompose can potentially be shortened. This offers a sense of hope for finding a natural means to reduce the plastic already present in the waste stream.