Microscopic Michigan: Dr. Emily Geiger is taming wild yeast on the shores of Superior

Dr. Emily Geiger is the founder of Craft Cultures, a commercial yeast company in Hancock, Michigan // Photo by Sarah Bird

Dr. Emily Geiger is the founder of Craft Cultures, a commercial yeast company in Hancock, Michigan. Here, she focuses the microscope on a liquid yeast sample under 1000x magnification // Photo by Sarah Bird

Walk along the shoreline of Lake Superior outside of the Upper Peninsula town of Hancock, Michigan, and you might stumble across a half-filled mason jar covered in a cloth. Don’t disturb it. It’s not a forgotten glass of beer from a picnic or beach party, but one of Dr. Emily Geiger’s carefully laid traps.

Call her the yeast whisperer. Dr. Geiger, the owner and founder of the commercial yeast company, Craft Cultures, wanders the shores and woods of Lake Superior to capture wild strains, giving them a comfortable place to live and grow in the fermentors of Michigan craft breweries. By cultivating indigenous yeast, she is helping brewers, distillers, and cidermakers experiment on a new frontier of flavor.

She first had the idea to start a commercial yeast company while pursuing her doctorate at Michigan Tech and working as the resident microbiologist at Keweenaw Brewing Company. “[It took me] from being behind the book to contributing my skills,” says Dr. Geiger. “I fell in love with the collaborative nature of the craft beer industry, versus the research life which is competitive and fast-paced.”

Though she saw an opening in the industry and had the expertise to match, the timing in life for her to start her own business was not ideal. Her graduate program was consuming most of her time and capital, as student loans piled up. But the opportunity felt too promising to not take the chance.

Craft Cultures fills a niche in Michigan’s craft beer industry that is especially lacking in competition. When Dr. Geiger started the company, there wasn’t anyone in the state working in commercial yeast. “The beer industry was booming and I knew that if I didn’t start [Craft Cultures], someone else would,” says Dr. Geiger.

Dr. Geiger holding a petri dish with yeast culture // Photo by Sarah Bird

Dr. Geiger demonstrating what a yeast colony might look like. This particular petri dish contains a pure culture of yeast colonies that were plated on solid agar // Photo by Sarah Bird

She started Craft Cultures in 2013  and was renting space out of an old winery that was too big, with heating costs that were astronomical. These days though, she works out of a startup incubator at Finlandia University where she prepares her most sought-after offerings—unique strains collected from the Upper Peninsula.

“As a hobby, I’ll trap yeast, and those indigenous strains are available for everyone. And they’re sequenced. The Eagle River Ale Yeast is our best-selling strain.”

The strain is a spicy, phenolic Belgian yeast, isolated from the shores of Lake Superior near Eagle River, Michigan. It is one of seven yeast strains sold by Craft Cultures that are indigenous to Michigan. The full indigenous lineup ranges from funky Brettanomyces and Belgian strains to clean lager yeast, all collected in traps from different places along the Upper Peninsula.

To capture these indigenous strains, Dr. Geiger sets up mason jars filled with wort (unfermented beer). She covers the “trap” with cheesecloth to keep it free of insects, sets it in a desired location, and checks on it every 48 hours. If the trap is cloudy, she takes it back to the lab to propagate the colonies and eventually isolate the strain.

Each strain is evaluated for the presence of enzymes necessary for fermentation and for tolerance to alcohol. It’s at this point that Dr. Geiger brews a five-gallon batch of beer to suss out the real personality of the yeast strain, assessing whether the flavors produced are favorable for brewing. 

In addition to indigenous yeast, Craft Cultures sells 52 traditional brewing strains and partners with breweries to isolate proprietary strains of yeast.

“With our isolation projects, [a customer] will send me a substrate. A tequila distillery just sent me agave, so I isolated yeast from an agave sample,” Dr. Geiger explains. “A distillery growing its own grain sent me their grain—we set up yeast traps, and I isolated yeast from those.” Without marketing her business, Dr. Geiger has garnered partnerships with breweries from all over Michigan, plus a few in California, Rhode Island, and even Korea. 

Some of the specialized yeast strains, including the indigenous Eagle River Ale Yeast strain (left), that Craft Cultures offers for commercial and home brewers // Photo by Sarah Bird

Some of the specialized yeast strains, including the indigenous Eagle River Ale Yeast strain (left), that Craft Cultures offers for commercial and home brewers // Photo by Sarah Bird

Craft breweries are continuing to advertise their use of local ingredients, but usually that refers more to grains and hops. But for Michigan breweries looking to make beers that are 100 percent local, they now have options for local yeast—much of it from Craft Cultures. Breweries commend Dr. Geiger for adding a new layer of creativity to the industry.

“We worked with New Holland Brewing [makers of Dragon’s Milk Bourbon Barrel-Aged Stout and Mad Hatter Midwest IPA],” says Dr. Geiger. “They are really pleased with the fact that we’re adding new flavors to the industry. The same styles are being made [by breweries using the same commercially available yeast]. With our yeast, there is more versatility.”

Though support has been enthusiastic and growth consistent, Dr. Geiger continues to keep Craft Cultures as a 15 to 20 hours-per-week side gig. She is still a microbiologist for Keweenaw Brewing Company, an assistant professor at Finlandia University, and an adjunct professor at Gogebic Community College. 

At first glance, it may seem inconceivable that Dr. Geiger hasn’t taken the leap to pursue Craft Cultures as a full-time venture. The opportunity is hers for the taking—she’s giving brewers an edge in an increasingly competitive industry—but for a single, relatable reason that resonates with many of Americans. 

“I want to do [Craft Cultures] full time, however I have huge student loans,” explains Dr. Geiger. “[The business] is self-sustaining, but I don’t take a draw from the company yet. My biggest challenge is taking that jump.”

For now, Dr. Geiger is part of a loan forgiveness program through her public service position as an assistant professor. She hopes that if the company continues to grow, she’ll be able to take the leap to full time.

Scott Mouw, Dr. Geiger's business partner, uses a refractometer to get an original gravity reading of sterile wort that will be added to their yeast "traps" // Photo by Sarah Bird

Scott Mouw, Dr. Geiger’s business partner, uses a refractometer to get an original gravity reading of sterile wort that will be added to their yeast “traps” // Photo by Sarah Bird

Despite managing three jobs and her own business, Dr. Geiger cultures every single customer request to-order, growing yeast from a 50-milliliter culture to the required cell count for a brewery’s batch size and starting gravity.

“What’s unique is that we’re able to customize cell count to starting gravity. If [our customer] is making a high-gravity beer, we can up cell counts,” says Dr. Geiger. And she does so maintaining a lead time that’s competitive with the major yeast suppliers.

How does she do this and work three jobs? Dr. Geiger gives partial credit to her time management skills, but says the autonomy of the yeast is what has really made it possible for Craft Cultures to thrive as a side hustle.

“You have to have sterile techniques, but I don’t have to be there 24/7,” she explains. “The yeast are doing their own thing.”

But without Dr. Geiger taking a chance on Craft Cultures, the yeast would still be floating wild around the shores of the U.P. And she has advice for other female entrepreneurs interested in the craft beer industry. 

“Be fearless. If you have an idea and believe in it, just try.”



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