Dana Davis leads a Nature of Life field course for incoming freshman.
Dana Davis was taking a quick break from teaching students about microbiology as an instructor for Nature of Life at a College of Biological Sciences (CBS) field station when he noticed a coyote boldly traipsing across the station soccer field. Halfway across the field, the coyote paused and left a steaming pile of feces, or “scat.”
It was exactly what Davis needed to finish classes for the day. He rushed to collect it before purifying a sample in his lab and plating it on a petri dish with a nutrient-dense agar used in laboratory settings to support the subsequent growth of yeast colonies. Later, the plated samples would be used as model results of what yeast colonies look like, but they’d also contribute to Davis’s newest research project. Since Davis started utilizing CBS-affiliated field sites such as Cedar Creek Ecosystem Science Reserve (CCESR) and Itasca Biological Station and Laboratories (IBSL) to collect scat from wildlife five years ago, he’s made a few surprising discoveries.
His first screenings revealed that the presence of Candida albicans — a yeast species commonly known for being present in humans and occasionally causing health problems like thrush, diaper rash, and candidiasis — may be relatively common in wildlife. “What was more interesting, though, was that the vast majority of things that [we] identified or cultured had never been characterized or identified before,” says Davis. “There were brand new species.”
Davis thinks he’s found about 12 new species of yeast. Expanding his scope of research has been a surprising, invigorating, and career-altering journey.
From beer to bear poop
In many ways, Davis credits his passion to brewing beer.
“Most things in my life revolve around or are facilitated by beer,” laughs Davis. He got his start in microbiological research as a Ph.D. student studying Saccharomyces cerevisiae, a model species commonly known as “brewer’s yeast.” It’s a staple for a good, malty brew. But in his transition to a postdoctoral research position, Davis made the switch to C. albicans, a more niche microbial system that was gaining traction in molecular genetic research.
“I thought it would be more fun to break into something new,” he says. “Candida albicans was becoming a focus of molecular genetic research, so at the time I felt I could get on the ground floor.” In his current research, Davis studies how yeasts, particularly C. albicans, respond to environmental changes. But in 2014, while Davis co-instructed a microbiology-based brewing course with friend and fellow scientist, Jim Cotner, Davis and Cotner began brainstorming new ways to take the C. albicans research outdoors.
“There are very few reports of Candida albicans outside of humans, and most have been related to zoo animals that died of candidiasis.” Davis found himself curious about the broader scope of the yeast — in wildlife especially. Understanding the conditions C. albicans thrive in could inform medical practice. But looking for yeasts in wild animals could also paint a larger picture of mammalian health and spread of disease. I.e., why can some immune systems respond to specific yeasts better than others? Can yeasts pass from host to host -– from dog to owner, deer to mouse, etc.? How do they mutate along the way?
He had to know. “Over beers one day, I said to Jim – let’s sample animal scat! This might be a fun project for [an undergrad], and he thought it was a great idea,” says Davis.
Field friends
In the summer of 2011, Davis sent an undergraduate researcher named Jhoset Burgos to collect scat samples from various field stations. When the initial findings were successful, Davis looked for new ways to integrate the research into his undergraduate courses. Davis has been especially successful integrating the work into his summer Nature of Life modules, which are hours-long biology classes designed for a CBS freshman orientation.
These modules are held at both CCESR and IBSL. Both field stations affiliated with CBS have frequent wildlife visitors — bears, wolves, foxes, deer, mice, and more — whose scat is relatively easy to find if you know where to look. Davis does.
In a single day, Davis can venture outdoors with a handful of students, scout out wildlife scat, return to the lab, then purify and plate the poop samples on a nutrient-dense agar so lingering yeast cells can grow into colonies in the next day or so and then be studied and identified. The growths are often fuzzy, colorful, or have unique patterns, and make for a visually compelling way to engage students.
Outside of class, trained students can collect the scat quite easily on their own, and have already been hired to do so utilizing outdoor spaces such as CCESR, protected University wildlife areas, IBSL, and elsewhere. CCESR is an especially useful resource given its acreage, proximity to the University of Minnesota campuses, and long history of engaging with student research.
Davis is hopeful that the implications of finding C. albicans in wildlife and the discovery of new yeast species, in combination with the project’s educational benefits, could levy support from new funders. “Students were so excited about collecting scat samples and grinding them up and plating,” says Davis. “They were definitely into it. I just decided — why not loop students into something that’s contributing to real research as well?” – Adara Taylor