Fungi: A Novel Way of Dealing with an Unpleasant Problem
Despite their name, disposable diapers are notoriously difficult to dispose of. Studies of landfills suggest they may take centuries to rot away. But Alethia Vázquez-Morillas of the Autonomous Metropolitan University in Mexico City thinks she has found a method of speeding the process up.
As she and her colleagues describe in Waste Management, cultivating the right type of mushroom on soiled diapers can break down 90% of the material they are made of within two months. Within four, they are degraded completely. What is more, she says, despite their unsavoury diet, the fungi in question, Pleurotus ostreatus (better known as oyster mushrooms), are safe to eat. To prove the point she has, indeed, eaten them.
The culinary use of oyster mushrooms was one reason why she picked them for the experiment. The species is frequently used in stir-fries and is often added to soups. The other reason was that Pleurotus ostreatus is widely used in what is known as mycoremediation—the deployment of fungi to clean up waste. It is, for example, already grown on agricultural materials such as wheat and barley straw, and industrial waste like coffee grounds and the leftovers from making tequila. Dr Vázquez-Morillas and her colleagues were trying to extend the oyster mushroom’s own culinary range.
The reason diapers are difficult to break down has nothing to do with their use. Even a clean diaper would hang around for a long time in a dump. The main ingredient of a diaper is cellulose, an annoyingly persistent material. Pleurotus, however, grows on dead or dying trees in the wild and is thus well provided with enzymes that break cellulose down. And, since Mexicans alone throw away 5 billion diapers every year, there is plenty of material from this source for them to get their mycelia into.
In practice, overcoming the yuck factor might be an insuperable barrier to marketing diaper-grown fungi. Mycoremediation of this sort does not, however, depend for its success on selling the results. Merely getting rid of what would otherwise hang around indefinitely is worthwhile. And of the fungi themselves, Dr Vázquez-Morillas observes, “they are cleaner than most of the vegetables you can find in the market, at least in Mexico.”
via The Economist
