All plants and animals eventually die, and their remains break down into their building blocks. Ancient forests die and decay and, over millennia, are transformed into oil. In the form of oil, these ancient forests are reprocessed into modern plastics. So this should be true for plastic, right? Well, yes and no. Mostly no. There are some biodegradable plastics, such as those made from starch from corn or tapioca. And others made from fermented plant sugars or from cellulose. In fact, in the 19th century early plastics were made from organic materials, such as cellulose, and were biodegradable as a result. However, most modern plastics are made from hydrocarbons 

The production of plastics made from petroleum has boomed since the mid-20th century. Sadly, these are non-biodegradable; they do not decompose naturally. Instead, they break down into smaller and smaller bits, but those bits of microplastic stay in our environment. They are in our food-chain, our water, our own bodies even. And so, we have a waste problem. A world-wide one.

Biological Decomposers

Bioremediation is a fancy word for any process that uses microorganisms, fungi, algae, green plants or their enzymes in order to remove or degrade pollutants. It is done using natural means rather than mechanical ones like incineration. Decomposers can be fungi, bacteria, worms, and insects. When we think of decomposers, we think of them eating dead plants and animals. Your compost heap is a good example of using natural decomposers. Enzymes that break down plastics can be found in the gut of Blaptica dubia, a South American cockroach. However, the cockroaches themselves are not known to feed on plastic. There are some kinds of bacteria, such as Flavobacterium, that can and do eat plastic. The first one discovered was Ideonella sakaiensis 201-F6. It is popular with bioengineers working to create genetically modified bacteria in the lab. On the other hand, Comamonas is another bacteria that is found naturally occurring in soil all over the world. It sees plastic waste as a tasty meal! 

You’ve seen fungi growing on dead wood, right? To live and grow, they release enzymes that decompose dead plants and animals. Then the fungi can absorb nutrients from the organisms as they are decomposing. One of the most effective fungus, Pestalotiopsis, lives in the rainforests of Ecuador. It thrives even in places with very low oxygen levels, so it potentially can be used to decompose plastic trash in landfills. Some researchers are working on bioengineering new plastic-eating bacteria. But, according to Dr. Ludmilla Aristilde of Northwestern University, the naturally occurring bacteria are the best.