CHARLES BERGQUIST: So, Flora, we’ve talked about how fungi could help with planetary problems. But this next story is about what happens when a fungus itself becomes the problem, not in The Last of Us sense but in a way that could actually destroy a town.

FLORA LICHTMAN: Yes, this one doesn’t go down as easy. A Tennessee town near the Jack Daniels Whiskey Distillery is awash in a fungus that coats trees, houses, stop signs, you name it. It is appropriately called whiskey fungus.

CHARLES BERGQUIST: Uh. So I’m pro whiskey. But a town-destroying fungus fueled by whiskey, it’s a little hard to swallow.

FLORA LICHTMAN: I spoke to Dr. James A Scott, a professor at the University of Toronto, who solved the mystery of where this fungus sits on the fungal family tree. And he slung me all the neat details on whiskey fungus and its booze-fueled superpower. Well, tell me about this fungus. First of all, what is it feeding on?

JAMES A. SCOTT: So the fungus can feed on ethanol as you’d expect from the habitat that it lives in. But, equally, you can grow it in a laboratory in the absence of ethanol. And probably in nature, it also grows in the absence of ethanol. The process of distillation is intended to concentrate the alcohol.

And then certain kinds of alcohol like whiskey tequila, rum– it’s a long list– after the distillation process are placed in barrels and then aged for a period of time. And that period of time that the alcohol spends in the barrel imparts it with certain flavors and certain characteristics that are desirable. And it’s during the aging process where in these porous wooden barrels the ethanol escapes.

FLORA LICHTMAN: So it’s actually just feeding on the whiskey?

JAMES A. SCOTT: It feeds on the whiskey that essentially leaks out as vapor from the barrels and into the surrounding environment.

FLORA LICHTMAN: And can it bubble up near any kind of distillery or is this fungus just like a straight up whiskey gal?

JAMES A. SCOTT: So whiskey and aged spirits are where I’ve found most of this. But then I have to admit that that’s largely where I’ve spent time studying it. There are certainly other processes that are industrial processes that emit alcohol vapor into the air.

For example, baking is one. When you use bread yeast to rise flour, it produces ethanol. And during the baking process of bread, that ethanol is off gased through the vent and into the environment. So we find around large commercial bakeries that sometimes there’s an accumulation of this fungus, at least around the exhaust vents from ovens and sometimes it disperses a little bit further than that as well.

FLORA LICHTMAN: What does it look like?

JAMES A. SCOTT: It’s hard to describe. It’s a sort of streaky, black fungus that gets on all kinds of surfaces. So it’s not limited to the kinds of surfaces where you’d normally see fungus like organic surfaces.

This fungus can grow on unusual things like fences, and road signs, and cars. It can grow on window glass, a range of different things that you wouldn’t expect fungus to grow on. And it produces a sort of streaky, black growth.

When there’s a lot of alcohol emission, that growth can actually get quite thickened into a thickened crust. It’s not at that point a single fungus that’s involved. It’s probably a kind of evolving biofilm that includes many different fungi. But species of Baudoinia, which is this group of fungi that we call whiskey fungi are likely the primary colonists that are sort of the founding members of that biofilm.

FLORA LICHTMAN: Oh, wow. So there’s a whole ecosystem. In this Tennessee town near the Jack Daniels Distillery, residents have complained for years that this fungus is causing property damage. There’s even a lawsuit from property owners. How destructive is it or can it be?

JAMES A. SCOTT: Well, once the fungus gets onto surfaces, it tends to anchor on and hold on fairly well. So it can be removed, but it’s only removed through mechanical action like pressure washing or scrubbing or a combination of both. So those processes alone can cause accelerated aging of materials.

And the fungus attaching on does some damage as well. So it causes the materials to break down. But I should say that there are other jurisdictions where there’s a lot more tolerance and even a kind of celebration of this fungus.

FLORA LICHTMAN: Really?

JAMES A. SCOTT: I remember one situation where I was in France near Bordeaux working on this fungus. And I was taking a break from touring distilleries.

FLORA LICHTMAN: First of all, this sounds like a good job.

JAMES A. SCOTT: Sitting at a little cafe– it is a great job. Sitting at a little cafe And as I was sitting at the cafe, I looked down at the bistro table. And the pattern of the Formica on the surface of the bistro table was modeled after the pattern of this fungus growing on the walls in the town. So I thought here’s a culture that is actually, in a way, celebrating this patina of fungal growth on surfaces in a way that we don’t necessarily hear.

FLORA LICHTMAN: Can it make people sick?

JAMES A. SCOTT: That’s not really clear. As far as I know, have been no studies looking specifically at what this fungus does or doesn’t do. I suspect that any fungus that if there’s enough exposure to it, then it could probably have some deleterious effects.

But that’s not a unique property of this fungus. It’s just something that would be characteristic of any fungus. But any specific effects related to this fungus as far as I know just haven’t been studied.

FLORA LICHTMAN: That’s about all we have time for. Thank you, Dr. Scott.

JAMES A. SCOTT: My pleasure. Thanks very much for having me, Flora.

FLORA LICHTMAN: Dr. James A. Scott is a professor in the School of Public Health at the University of Toronto based in Toronto, Canada.

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