Plastic-eating Organisms

Simon Levien

Diatoms eating plastic
Diatoms, the most common type of algae, are considered as another potentially viable plastic eater of the future

Over eight million tons of plastic are dumped into the oceans every year. The forget about it mentality pervades society, and they ignore a massive problem that plagues marine life. The newest data, according to a study published in Science, claims that the sheer tonnage of plastic burdening oceans every year is equal to 5 plastic bags for every foot of coastline across the globe! These massive plastic dumps float and accumulate into giant swirls of muck at the ocean surface. Some have even earned their own names, like the Great Pacific Garbage Patch, akin to some geographic region you might see in an Atlas. But all that plastic is ruining ecosystems, trapping and asphyxiating marine life, as well as interfering with basic biological processes. However, potential solutions are on the rise, with lots of research going into organisms that can digest plastic and turn it into degradable or biologically recyclable wastes such as free carbon and hydrogen. In the future, perhaps artificially introduced alga, bacterium, or worm populations can help reduce plastic in the future and revolutionize waste disposal.

Most plastics cannot biodegrade, remaining in the environment for thousands of years. Plastics are typically derived from propylene, a derivative of petroleum. When these monomers of propylene link together in plastics they form long chains called polypropylene. However, these compounds do not naturally occur in nature, so no organism ever evolved to solely/mainly depend on them as a resource. Kenneth Peters, an organic chemist at Stanford University, said, “Nature doesn’t make things like that, so organisms have never seen that before.”

However, some species have been discovered to be able to actually consume polypropylene when introduced to the substance. Specifically, mealworms had been discovered to consume styrofoam and other types of plastic by utilizing certain strains of gut bacteria that convert the substance into usable organic compounds. Other species of worms contain digestive microbiomes that carry bacterial strains that can degrade polypropylene, but only if its host worm eats it.

This novel function of waxworms and mealworms might perhaps be one of the biggest breakthroughs in environmental science in the last decade. However, practical applications are yet to be developed. As with the introduction of any new species, ecologists take major risks. Introducing populations of these worms into foreign areas could prove futile. Worms could be snatched up by hungry fish and birds left and right, or they might find the environment unworkable until the population runs to 0. On the other hand, they could begin to dominate and outcompete indigenous and endemic species. Maybe even they would never accomplish the original goal of eating plastic, finding other, better food sources in the region. All environmental scientists can do is make their best predictions and roll the dice.

Similarly, a recent German study in Current Biology proposed that a group of plastic-digesting caterpillars might not have that true capability. Yes, they may eat plastic, but the wastes they produce might be biologically identical to polypropylene. Instead of eliminating the problem, these caterpillars could generate microplastics, another danger to the environment. This study casts doubt on the effectiveness of other species’ gut bacteria, like the aforementioned worms. As of this article, waxworms and mealworms have yet to be reevaluated.

While potential plastic-eating organisms could revolutionize plastic disposal and mitigate the effects of waste dumping, it cannot be a substitute for common sense recycling. Much of the waste in the oceans is a result of the fact that a measly 10% of plastics are recycled in the United States (we are also the country with the fifth highest ecological footprint). Plastic eating organisms might help us significantly reduce garbage patches across the globe, but it would be but a blip in the ecological record if we don’t stop contributing to that waste.

Editor: Maria ‘Stefi’ Ticsa