Plastic is changing into a plague on Earth. Not solely are landfills bursting with it, however it has additionally polluted our oceans to the level {that a} tiny creature that had apparently made microplastics a part of its weight loss plan was named Eurythenes plasticus. Can we probably maintain again the unfold of a cloth that piles up quicker than it could ever decay?
There may be an answer, and that answer is fungus. Researchers from the University of Kelaniya and the University of Peradeniya in Sri Lanka have found species of fungi that may break down polyethylene—the identical kind of plastic used for baggage, bottles, cling wrap, takeout containers, and extra. These fungi have one factor in frequent: They usually break down hardwood, which in any other case doesn’t decay rapidly. While lots of of fungi and different microorganisms are recognized to break down varied plastics, it was beforehand unknown that these specific hardwood-eating species could degrade polyethylene.
“Microbial biodegradation of plastics is a promising strategy to depolymerize petroleum-based plastics into monomers or mineralize them into carbon dioxide and water,” the researchers stated in a examine lately revealed in PLOS ONE.
The breakdown
How tough can it be to break down hardwoods akin to ironwood or ebony? It’s onerous (pun considerably meant) as a result of the wooden is held collectively by the polymer lignin, which is present in the partitions of cells inside the wooden and provides it its power. Lignin is hard however can be damaged down and depolymerized by the proper enzymes.
When the analysis staff discovered useless hardwood timber decaying in a forest reserve, they grew to become curious as a result of these timber don’t break down simply. They gathered fungi samples that they faraway from the wooden and introduced them again to their lab. The fungi had been then remoted by species, with every species positioned into a unique container and given items of hardwood and sheets of polyethylene to feast on.
The staff needed to examine the plastic-eating talents of the fungal species and decide every species’ manufacturing of an enzyme that breaks aside lignin. The extent to which plastic and hardwood deteriorated was decided by evaluating the weight of these supplies earlier than and after publicity to the fungi. Over 45 days, the wooden misplaced wherever from just a little over 1 p.c to almost 36 p.c of its weight. This weight reduction occurred as a result of the fungi broke down the lignin and cellulose into merchandise that included carbon dioxide.
Plastic additionally misplaced weight by being transformed to less complicated molecules by enzymes from the fungi for the identical period of time, shedding almost half of its mass. Polyethylene is often a hydrophobic, or water resistant, materials, however it regularly loses that property because it degrades. It additionally turns into extra fragile. As the fungi did their work, the polyethylene grew to become more and more fragile and misplaced its capability to repel water.
Plastic for dinner
The researchers additionally needed to see what the fungi would do in the event that they got no wooden and solely plastic. It was potential they’d eat much less plastic with out their favourite meals in sight since one thing about wooden presumably prompts their digestive enzymes. But what occurred was quite stunning. “The most striking feature of the experiment was that all the isolates showed elevated degradation of [polyethylene] in the absence of wood than that in the presence of wood,” the researchers stated in the identical examine.
These fungi want carbon to survive. While wooden is their most well-liked carbon supply, when it was not accessible, polyethylene supplied an alternate. Their degradation of extra plastic, when it was supplied to them, confirmed that they had been simply in a position to metabolically adapt and alter up their weight loss plan when there was no wooden round.
Lignin and polyethylene have chemical properties in frequent. When they used their lignin-degrading enzymes with out precise lignin, they evidently had no drawback switching to plastic.
In the future, it’s potential that fungi could be used to break down plastic rubbish on a bigger scale, however bigger operations utilizing fungus to clear up waste clogged by plastic will take time to develop. Until then, we should use biodegradable supplies every time potential and recycle all that plastic.
PLOS One, 2023. DOI: 10.1371/journal.pone.0288133