Hunting for bioluminescent mushrooms

Here’s what I was told: Get away from the city, go during a new moon and keep my flashlight off. When the sky faded black enough to spot stars twinkling, I’d be able to see mushrooms glowing. There are about 100,000 species of fungi, but only about 80 of them bioluminescence, or glow in the dark. They pop up in tropical and temperate forests in the Americas, Japan, Southeast Asia, Australia and South Africa.

They emit green light, a result of nearly the same chemical reaction that illuminates the belly of a firefly or the skin of a squid, only the resulting light is constant in the mushroom, not on-demand or reactive as in some insects or marine animals. The molecules responsible for the colours are different too. And in a study published on April 26 in Science Advances, researchers have finally revealed what’s going on inside these flamboyant fungi — at a molecular scale.

With mushroom season approaching, you can see them glowing, too, and you don’t even need to leave the country. But you’ll need to practice patience and prepare for disappointment when heading out on the hunt. In a boggy forest near Asheville, North Carolina, USA, I once spent a night two summers ago tracking down three species of glowing mushrooms. Lost in the dark with a dying phone and a forager known locally as the Mushroom Man, I learned that mushrooms are unpredictable. “You can’t always get what you want, when you want it,” said Alan Muskat, who leads quirky foraging tours with his company, No Taste Like Home. I learned a few other lessons as well.


Getting to know the object

In all bioluminescent organisms, a small molecule called luciferin interacts with oxygen and a bigger protein called luciferase, creating chemical energy that is eventually released in the form of cold light. Every organism has its own version of luciferin and luciferase, with individual properties that could prove useful.

For example, one group has unsuccessfully tried to make glowing plants by splicing in genes from bioluminescent bacteria. But the chemicals involved in fungal bioluminescence may be more compatible with plants. “Maybe it will be as difficult as people traveling to Mars or other galaxies, but maybe we will use it,” said Zinaida Kaskova, a chemist at Pirogov Russian National Research Medical University in Moscow, Russia who led the study of bioluminescent mushroom molecules. Unlike other bioluminescent organisms, fungi emit a constant light, possibly to attract spore-transporting insects that dims and intensifies according to a circadian clock that still isn’t quite understood.

In the Japanese island Hachijo-jima, tiny, common mushrooms — known locally as hato-no-hi, or pigeon fire — glow along forest paths during the rainy season from May through September. But among the thousands of fungi that grow in the subsection of the southern Appalachian Mountains I was exploring, there are a few glowers. The large, orange fruiting bodies of Omphalotus olearius, or jack-o’-lantern, appear in great numbers around June to September. Then there’s Panellus stipticus, or bitter oyster, a summer mushroom that looks like a tiny, tan fan growing on sticks. But first, you have to find them.

Don’t go into the woods alone at night. Find a guide in a local mushroom hunting group. My guide, Alan, is not a professional mycologist, but he has decades of experience. A week before we met, he enlisted ‘informants’ who provided leads on where to find our three mushrooms. These included photos and detailed descriptions of what trail they were on, how far down it they would be found and even the unique characteristics and type of tree they were under.


A surprise in the sunlight

After an unsatisfying evening, we went looking for other mushrooms just for fun the next day. Unexpectedly, we found hundreds of jack-o’-lanterns in the daylight. This is why you should always bring a basket. It should be wood or natural fibre with a lattice bottom so the mushrooms’ spores can return to the forest floor. To collect the mushrooms, bring a knife and a brush. Unless you want your ’shrooms to turn into slime, bring wax paper or a paper bag, never plastic.

At home, I placed my fresh jack-o’-lanterns, gills up, in a cardboard box in the corner of a windowless bathroom and waited for my eyes to adjust. It didn’t take long before I saw the little glowing gills. They appeared to be breathing. Hello there, my neon green friend. I’ve heard so much about you.