2017-04-28 10:01:02
Hunting Mushrooms, and What Makes Some Glow in the Dark

10:01, April 28 464 0

PISGAH NATIONAL FOREST, N.C. — 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 bioluminesce, 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 colors are different too. And in a study published on Wednesday 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, N.C., 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, near Asheville. “This isn’t like a convenience store.”

I learned a few other lessons as well.

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 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.

On 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. And in the Atlantic forest of southern Brazil, Neonthopanus gardneri, or flor de coco, resembles a large, radioactive flower from another planet.

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 through September.

Then there’s Panellus stipticus, or bitter oyster, a summer mushroom that looks like a tiny, tan fan growing on sticks. You can also find Armillaria mellea, a sometimes-parasitic fungus also known as honey mushroom that appears in the fall and makes wood look as if it’s glowing.

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. A good place to start is the North American Mycological Association, an organization of professional and amateur mycologists.

My guide, Mr. Muskat, is not a professional mycologist, but he has decades of experience — enough to write a book. His weird sense of humor and Tao-like wisdom made a dragging hunt less taxing. 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.

But tips don’t always pan out. We spent two hours wandering down a trail searching for honey mushrooms, only to find after we had turned back that the fungus was under the tree we had passed at the trail head.

Foxfire is the emberlike glow that appears when a honey mushroom’s rootlike filaments infect and start killing a deciduous tree, often an oak. To see whether the fungus we had found would produce a glow, we looked for the dark, stringy infestation known as a rhizomorph, or shoestring rot, because that’s what it looks like, and that’s what it does to the wood.

Mr. Muskat found a rhizomorph at the bottom of our tree, but the healthy-looking wood and the dead-looking mushroom suggested it wouldn’t glow. Still, he shouted “lights out,” and we waited for even a faint light. As we allowed our eyes to adapt to the darkness — it should take around 20 minutes — we played a brain game called minute mystery to pass the time.

The honey mushroom we found never produced any glowing wood, but while I sat in the dark, I spotted tiny green dots: an unexpected cluster of bitter oyster, one of the other glowing species, lined up on a small stick.

More bitter oyster appeared, as if out of nowhere, in another spot where we were disappointed yet again by decomposing jack-o’-lantern mushrooms. The dead mushrooms looked like burned pancakes that were teeming with insects, emitting only a dim, ghostly, pewter aura.

As a mushroom’s metabolism shuts down in death, so does its ability to create light, said Dr. Kaskova: “Fewer and fewer molecules of luciferin are synthesized, so the glowing becomes weaker and weaker.”

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 fiber 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.