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9 Molds Trying to Take Over Your Kitchen

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At some point in your life, you’ve likely rummaged around the kitchen for a tasty snack, opened it up, and discovered that your treat has been cheerfully consumed by a colorful fuzz. Although your reaction was probably simple—“Ick, mold!”—not all molds are made alike. There are actually a couple thousand of genera of mold within the kingdom Fungi, and many more species, each with its own special traits and talents. Specialists, generalists, molds that like it damp, or dry, or fruity—they’re living and breeding among us.

The fuzz you see is actually just the fruiting body of any given mold—namely, its spores. These hang out trying to catch a breeze on to something organic to grow on. Under the hairy bit is the body of the mold, the mycelium. If you were to cut open a moldy bagel instead of chucking it, you’d find that the mycelium’s feathery strands, called hyphae, had already feasted on the inside, excreting digestive enzymes to turn it into a smelly web.

Just what do these molds want with us and our edibles? “To reproduce and take over the world,” says Kathie Hodge, an associate professor of mycology at Cornell University. Hodge's research focuses on the classification of fungi—including molds. She also edits the Cornell Mushroom Blog.

Hodge says the ecological function of molds is to act as recyclers. But that definition “gives them short shrift," she adds. "Molds live their own vibrant and interesting lives.” Sometimes their drama plays out in your kitchen.

Here’s a tour of some of what Hodge calls the “small and elegant” entities waiting to turn your fridge into a fascinating fungus zoo:

1. RHIZOPUS STOLONIFER, A.K.A. BLACK BREAD MOLD

It’s likely that this white-then-black species is the one that took over your bagel. How? Hodge says spores may have landed on it back at the bakery, or maybe they first infiltrated some breadcrumbs that fell unnoticed behind your toaster. Rhizopus stolonifer is a bread specialist, getting to it early, eating it like crazy, and growing incredibly fast. Molds love sugar, “and as anyone on a low-carb diet knows, bread is starch, which is basically sugar and easy to break down,” says Hodge. Is it safe to eat a Rhizopus-infected bagel? “It would taste disgusting, so don’t go there."

2. PENICILLIUM CHRYSOGENUM

Moldy Bread
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It’s also possible that this puffy bluish mold is your bread-eating culprit. Yes, Penicillium is the same genus that brings you lifesaving penicillin. But don’t try to use your blue bagel as a home remedy. “I can’t tell you how many times people have said, ‘I have a cut on my arm, should I put moldy bread on it?’” sighs Hodge. Mold only morphs into antibiotics after it’s been extracted from its growth medium and purified in a lab and furthermore, the Pencillium group as a whole—there are over 300 species—is famous for making many and diverse toxins. Still, one species also makes blue cheese (Penicillium roqueforti), and another cures salami (Penicillium nalgiovense).

3. WALLEMIA SEBI

This is one of the true oddballs of the mold world—an extremophile that likes to live, as this name suggests, in extreme outposts. Extreme for a mold is a place that’s salty or super-sugary, and therefore, dehydrating. Enter Wallemia sebi, thick brownish blobs of which Hodge once found floating in her maple syrup. “It’s really slow and patient,” she says, hiding out and waiting for its time to pounce. “So, if you eat your maple syrup at a normal rate, you’re never going to see it.” Wallemia sebi is the source of some amount of controversy among Hodge’s colleagues. Some of them insist that it’s harmless. But remember, Hodge points out, “it’s been eating and excreting into your syrup. I highly recommend that people throw it out.”

4. ZYGOPHIALA JAMAICENSIS, A.K.A. FLYSPECK

flyspeck mold on green grapes
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This mold is commonly found growing on apples (and grapes), and is also known as flyspeck. Confusingly, flyspeck can be caused by a variety of mold species, varying by region and type of apple. Flyspecked apples are usually snubbed by consumers, despite the fact that their little black bumps are harmless and grow only on the skin. “It’s a hard life, being a plant,” says Hodge. “Every one I can think of has multiple fungal problems.” If you find flyspeck on your fruit at home, console yourself in the knowledge that it came in from the orchard and likely isn’t lurking in your cupboards.

5. FUSARIUM VERTICILLIODES, A.K.A. MAIZE EAR ROT

Ever peeled open an ear of corn and found a patch of pink sliming the kernels? That’s Fusarium verticilliodes, part of a huge genus that produces some truly terrible mycotoxins. It loooooves both the sweet corn you buy at the market and the field corn that’s manufactured into corn chips and fake-meat patties. And it can survive processing to cause things like estrogenic effects and immune suppression. Hence, Fusarium is highly regulated to try to keep it out of our food supply. And oh yeah, some species have also been used to make biological warfare agents.

6. BOTRYTIS CINEREA, A.K.A. NOBLE ROT FUNGUS

mold on strawberries
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Fluffy grey Botrytis cinerea will gladly sink its spores into the strawberries in your fruit bowl. It’s not particularly toxic, says Hodge, but it can gobble up fruit with lightening speed. It comes in with your berries from the field, where damp conditions make it hard to eradicate. The upside: This mold species is also known as “noble rot.” When it turns up (uninvited) on grapes in vineyards, it dries them out and concentrates their flavor; the grapes can then be used to make sweet wines like Sauternes (from France) and Tokaji Aszú (from Hungary and Slovakia).

7. ASPERGILLUS NIGER, A.K.A. BLACK MOLD

“This one is interesting,” says Hodge. “It can grow on onions—it shows up as black flecks between the layers. And it can also cause ear infections in humans.” But its talents don’t end there; Aspergillus niger also causes you to exclaim, “Ooh, lemons,” when you drink certain manufactured “lemony” beverages. (“No,” corrects Hodge. “It’s mold.”) Niger’s sister, Aspergillus oryzae, is used to make miso and soy sauce. And another, the parrot-green Aspergillus flavus, which favors peanuts and tree nuts, “is the worst fungus I can think of,” says Hodge. Its crimes against humanity include causing liver cancer.

8. DIPLODIA NATALENSIS

rotten lemon put on wooden table
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Most of us have reached into the vegetable drawer and pulled out a green lemon (thanks for nothing, Penicillium digitatum). But Diplodia natalenis is responsible for an unattractive darkening—and sometimes, mush-ening—of a lemon’s stem end. This mold is also devious; it lives inside the dead wood of trees back at the grove and doesn’t actually show itself until the fruit’s already been picked, packed, and stored in your refrigerator.

9. MUCOR CIRCINELLOIDES

This little guy (gal? Other? Molds can produce spores asexually and often sexually, too) is something of a generalist. It likes fruit, vegetables, and dairy. To wit: a virulent subspecies of Mucor circinelloides was implicated in a nausea- and vomit-inducing episode that affected more than 200 people who’d eaten some moldy yogurt back in 2013. How virulent? Tests showed that it could survive passage through the digestive tract of lab mice. But how it got into the yogurt in the first place remains a mystery.

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Why Adding Water to Your Whiskey Makes It Taste Better
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Don’t ever let people tease you for watering down your whiskey. If they’re true aficionados, they’ll know that adding a splash of water or a few cubes of ice to your drink will actually enhance its natural flavors. But how can something as flavorless as water make a barrel-aged scotch or bourbon taste even better? Chemists think they’ve found the answer.

As The Verge reports, researchers from the Linnæus University Centre for Biomaterials Chemistry in Sweden analyzed the molecular composition of whiskey in the presence of water. We already know that the molecule guaiacol is largely responsible for whiskey’s smoky taste and aroma. Guaiacol bonds to alcohol molecules, which means that in straight whisky that guaiacol flavor will be fairly evenly distributed throughout the cask. Alcohol is repelled by water, and guaiacol partially so. That means when a splash of the water is added to the beverage the alcohol gets pushed to the surface, dragging the guaiacol along with it. Concentrated at the top of the glass, the whiskey’s distinctive taste and scent is in the perfect position to be noticed by the drinker.

According to the team’s experiments, which they laid out in the journal Scientific Reports [PDF], whiskey that’s been diluted down to 40 percent to 45 percent alcohol content will start to show more guaiacol sloshing near the surface. Most commercial whiskey is already diluted before it's bottled, so the drink you order in a bar should fall within this range to begin with. Adding additional water or ice will boost the flavor-enhancing effect even further.

As for just how much water to add, the paper doesn’t specify. Whiskey lovers will just have to conduct some experiments of their own to see which ratios suit their palate.

[h/t NPR]

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Gray, George Robert; Hullmandel & Walton; Hullmandel, Charles Joseph; Mitchell, D. W / Public Doman
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Animals
DNA Tests Show ‘Extinct’ Penguin Species Never Existed
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Gray, George Robert; Hullmandel & Walton; Hullmandel, Charles Joseph; Mitchell, D. W / Public Doman

Science is a self-correcting process, ever in flux. Accepted hypotheses are overturned in the face of new information. The world isn’t flat after all. Disease isn’t caused by demons or wickedness. And that Hunter Island penguin? Yeah, apparently that was just a figment of our imaginations. Researchers writing in the Zoological Journal of the Linnean Society say the remains of one supposed species are in fact a “jumbled mixture” of bones from three extant species.

The bones were unearthed in the 1980s during the excavation of a prehistoric trash heap on Tasmania’s Hunter Island. Two scientists named Tets and O’Connor argued that the remains were different enough from other penguins to constitute their own genus and species, one which must have died out during the Holocene epoch. The proud potential penguin parents dubbed the apparently extinct bird Tasidyptes hunterivan, and that was that.

Except that this is science, where no story is ever really over. Other biologists were not satisfied with the evidence Tets and O’Connor presented. There were only four bones, and they all bore some resemblance to species that exist today. Fortunately, in 2017, we’ve got ways of making fossils talk. A research team led by Tess Cole of the University of Otago used DNA barcoding to examine the genetic code of each of the four bones.

“It was a fun and unexpected story,” Cole said in a statement, “because we show that Tasmania’s ‘extinct' penguin is not actually an extinct or unique penguin at all.”

Snares penguins dive into the water.
Snares penguins (Eudyptes robustus).
Brocken Inaglory, Wikimedia Commons // CC BY-SA 3.0

The bones were “a jumbled mixture of three living penguin species, from two genera": the Fiordland crested penguin or Tawaki (Eudyptes pachyrhynchus) and the Snares crested penguin (Eudyptes robustus), both of New Zealand, and the Australian little fairy penguin (Eudyptula novaehollandiae).

“This study shows how useful ancient DNA testing can be,” Cole said. “Not only does it help us identify new but extinct species, but it can help us rule out previously postulated species which did not exist, as in this case.”

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