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From the wing of a wasp, scientists discover a new beer-making yeast

July 4, 2017 at 6:20 PM EDT
If you enjoy a beer on a summer day, you can thank yeast, the microbes that ferment sugar into alcohol and give beer its character. After innumerable generations of using just two types of yeast, a lab in North Carolina has discovered a new yeast that produces a variety of flavors, and it comes from the weirdest source: bees. Science producer Nsikan Akpan reveals what the buzz is all about.

WILLIAM BRANGHAM: On this Independence Day, many Americans will no doubt be enjoying a beer or two. One of the essential ingredients in beer is yeast.

But, for 600 years, only two species of yeast, ale yeast and lager yeast, have been used for traditional brewing. But now a lab in North Carolina may have found a third species, and they found it in the strangest of places, on bees and wasps.

NewsHour science producer Nsikan Akpan and our “ScienceScope” team reveal what the buzz is all about.

NSIKAN AKPAN: It feels like beer brewers will do anything to spice up their booze. There’s pizza beer, banana split chocolate stout, beer with squid ink, and, of course, Rocky Mountain oyster stout, which is flavored with bull testicles.

All this fuss seems silly, when the foundation of alcohol’s flavor is plain old yeast. Yeast, these little microbes that take sugars and ferment them into alcohol, define a beer’s character.

Yet, for 10,000 years, beers have essentially relied on two types of bland yeast that basically add no flavors. Now a lab in North Carolina has discovered a new yeast species that produces an array of flavors without added ingredients.

Where did they find it? On bees. The story of bumblebeer begins at North Carolina State University, in the lab of Rob Dunn. Once a tropical forest ecologist, Dunn now explores the jungle that surrounds us, the one filled with bugs and microbes.

ROB DUNN: At some point, my lab shifted to focusing more on people’s daily lives, and that includes food, and it includes thinking about the biology of food.

NSIKAN AKPAN: One day three years ago, a colleague inquired if the lab knew of any microbes in the environment capable of making beer. Dunn and company instantly considered insect pollinators, like bees and wasps.

Here’s why. Yeast hang out in flower nectar, where the microbes feast on the boatloads of sugar. They then produce or ferment sweet aromas, which then attract the buzzing bugs.

ROB DUNN: We actually think, based on some work from colleagues in Italy, that it’s very likely that those first beers and breads were relying on yeasts from insects, too.

NSIKAN AKPAN: Back then, a bug carrying a fermenting yeast may have fallen into some wet grain. And, boom, welcome to the booze cruise. In fact, some scientists argue human agriculture started just to mass produce grains to make beer. The more beer we drink, the more yeast we have to grow.

ROB DUNN: Unambiguously, the most successful organism in the world is yeast. And so if you think about all of the yeasts we make everywhere for many of the products we make, they won.

NSIKAN AKPAN: But, today, where would you even start looking for a new beer-making yeast?

ANNE MADDEN: Part of this is science, and part of this feels more like an art that’s hard to describe.

NSIKAN AKPAN: Meet Anne Madden, the Dunn lab’s microbe wrangler. To search for unknown yeast, she started by catching a wild bee and a wild wasp. She then transferred every microbe from their bodies to a petri dish. Don’t fret. She didn’t commit mass bug-icide.

ANNE MADDEN: To make bumblebeer and all of the different bumblebeers that we have made since, we have killed two bugs. You have likely killed more bugs on your way to a bar to get beer than we did in the process of making it.

NSIKAN AKPAN: A couple days later, a forest of microbes appear on the dish. Then, in four steps, Madden combines her senses with technology. First, she looks to separate the yeast from bacteria or fungi.

ANNE MADDEN: It’s about understanding when something glistens in a certain way.

NSIKAN AKPAN: Next, she picks a handful of yeast candidates, grows them on a new dish, and then follows her nose.

ANNE MADDEN: You can smell the same smell both on that plate and in that final beer.

NSIKAN AKPAN: Her third task is running the DNA from these candidates through a national database to ensure her picks don’t cause disease.

ANNE MADDEN: It’s almost like a Google search through all other species that exist that have been documented.

NSIKAN AKPAN: The final step is a chemical test, because despite the long history of brewing, the genes and enzymes responsible for fermentation are largely unknown.

The survivors of this gauntlet land with John Sheppard at N.C. State’s research brew house.

JOHN SHEPPARD: In traditional beers that are lighter in character, like the traditional American lager, for example, you don’t want to overwhelm your taste, and so what the yeast does is very important.

A lot of wild yeasts, which are considered contamination in a normal brewing process, the reason why they’re not wanted is because they produce a lot of off-flavors that are not really desirable in the beer. So, to get a wild yeast that doesn’t produce these off-flavors can be difficult.

So, we did a little testing to see whether or not the yeast strains would be able to make beer, and we selected one. It came from a wasp, because this special yeast not only makes ethanol, but makes acid, and, as a result of that, we had a natural sour beer.

NSIKAN AKPAN: The bumblebeer yeast makes other flavors too, like a sweet honey taste without the addition of actual honey.

Craft sour beers often take months or years to make. Bumblebeer yeast can do the same in a matter of weeks. Local brewers have taken notice. The first suds made with bumblebeer yeast rolled out earlier this year.

Until next time, I’m Nsikan Akpan, and this is “ScienceScope” from the PBS NewsHour.

WILLIAM BRANGHAM: Nsikan tasted one of those beers and said that it was quite delicious.

You can read about how scientists are using this discovery to find more beer-producing yeasts made in the wild. That’s on our Web site,