The Mystery of the Canadian Whiskey Fungus
- 9:49 pm |
When James Scott attended the first day of a mycology course as a freshman in college, his plan was to cut class for the rest of the semester and fake his way through on borrowed notes. But in his lecture that day, the professor told a story about a fungus that lives on peach pits. No one, he said, knows how the fungus gets from one pit to the next. “If you go to an abandoned orchard and lie on your stomach under a tree for a week, watching which insects land on a peach and move to another one,” Scott remembers him saying, “you will know more about this fungus than anyone in the world.”
“It was something even I, an undergraduate who didn’t know anything, could do,” Scott says. “I could go out there and look for stuff.” In the space of one anecdote, Scott had become the sort of person who kept a microscope in his dorm room and decorated the walls with fungal family trees he drew himself. (He also plays the banjo.)
There are between 1.5 million and 5 million species of fungi on earth, and only 100,000 of them have been named according to the (arcane, ancient) rules in the International Code of Botanical Nomenclature. Of those, barely a fifth have gene sequences in GenBank, the world’s main storehouse of genomic data. Only a couple of hundred have been sequenced completely, mostly yeasts with commercial value. Magnified fungi look like a Dr. Seuss illustration rendered by Pixar. It’s a weird landscape, not to everyone’s taste. Among scientists, mycology is not considered a glamour field. “If you found a new deer, you’d be on the cover of Nature,” says John Taylor, a mycologist at UC Berkeley. “If you find a new fungus, you’re in the middle pages of Mycotaxon. But we’re not bitter.”
For hundreds of years, mycologists have named things the old-fashioned way—they’d put a sample under a microscope and describe the shape of its parts, the way it reproduced, the structure of its spores. The rules were typological: To designate a name, a researcher had to have a physical specimen called a type stored in an herbarium somewhere, a description in Latin, and sometimes an illustration of the microscopic structure, too.
That’s all changing now. The genome experts are taking over, planning to hoover up thousands of genetic samples and identify them by their DNA sequences. It’s a controversial shift in a field that has fought wars over nomenclature. Scott, though, was trained in the old school of mycological taxonomy, as practiced by a largely retired generation of scientists who could ID a fungus on sight. “James is a bit of a throwback,” says Keith Seifert, a research scientist with Agriculture and Agri-Food Canada, who has worked with Scott for years. “He’s interested in legacy knowledge.”
In Lakeshore, Scott found the black fungus as far as a mile away from the warehouse. And the closer it was, the thicker it grew, clinging like ashy cotton candy to walls, rooftops, even garden furniture. Under a microscope, it looked to be a mè9lange of different species, but much of it was thick-walled, rough-skinned stuff he’d never seen before. It looked like poorly hewn barrels, strung together end to end. Instantly, Scott realized where the distillery’s other researchers had gone wrong. “They would have taken a sample and scraped it over a petri dish,” Scott says. “And what would have grown were spores that just happened to be passively deposited.” Common fungi were commingled with the mystery stuff in the sample, and the common fungi grew faster. Come back in a couple of weeks and the petri dish would be covered with boring, familiar species—leading to a false conclusion.
Scott had a better way to culture the samples. He ground them up and sprinkled them into a petri dish. But then he put the dish under the microscope and, using an impossibly fine needle, picked out fragments of the rough-skinned fungus and transplanted them to their own dishes. He figured that with no other fungi to compete with, the Lakeshore fungus would flourish.
He waited about a month, came back, and found … not much of anything. Under a microscope the samples were clearly the same black barrel shapes. But his colonies were vanishingly small. Whatever it was, it wasn’t growing like it grew around the warehouse.
Making growth media for fungi is really just feeding them a dish they like to eat. So, on a hunch, Scott bought a bottle of Canadian Club. “I put maybe a shot of whiskey in a liter of agar and filled the petri plates with it,” Scott says. “That made it grow a hell of a lot faster.”
Chances were, Scott thought, it was the ethanol that the spores liked. But how was the fungus getting it in the wild? What connected the ethanol in those aging barrels to the black stuff on the walls of Lakeshore? Scott was still puzzled by this question when, several months later, he told his favorite wine seller about his mystery fungus. The importer, a sommelier-in-training, told him about the angels’ share—and Scott had his connection. The warehouse was venting vaporous ethanol.
A search of the mycology literature for fungi that grew in close proximity to ethanol led Scott to his first guess at what was on the warehouses: the “cellar fungus” Zasmidium cellare, which grows in thick layers inside wine-aging caves. Scott figured the warehouse and its environs were harboring a giant Zasmidium colony. “Based on the similarity of the habitat and the little bit of physical descriptions I could get, I thought that’s what it was,” he says.
Scott ordered a Zasmidium sample from the Centraalbureau voor Schimmelcultures in Utrecht, Netherlands—the world’s most important depot for fungal samples and genomes—and put it under the microscope. It didn’t look anything like the warehouse-staining fungus. Plus, that species grows only in the cool, controlled climate of an aging cave, and whatever was all over Lakeshore grew outside, over a wide temperature range.
He was stumped. All he had was an educated guess that his mystery fungus was part of a group called the “sooty molds.” It happened that an eminent expert on sooty molds, a scientist in his eighties named Stan Hughes, was at Agriculture Canada in Ottawa. And Hughes’ office was down the hall from Canada’s National Herbarium, one of the best collections of fungus specimens in North America. Scott packed his bags.