Seth Walk – Principal Investigator


Seth is an Associate Professor in the Department of Microbiology & Immunology at Montana State University. His research focuses on infectious diseases, microbial ecology, evolution and population genetics.

Phone: (406) 994-2649


Curriculum vitae for Seth Walk

Susan Broadaway – Lab Manager


Sue manages the Walk Lab. She also participates in projects examining Clostridioides difficile isolates from clinical specimens collected at medical centers around the US. This involves testing for the presence of C. difficile using culture and PCR, conducting cell-culture-based cytotoxin assays, and PCR ribotyping. Sue keeps trying to retire, but we won’t allow it (we can’t afford it!). Currently, she is on extended vacation and should (!) be back with us shortly.

Phone: 406-994-1744


Mark McAlpine – Lab Animal Manager


Mark’s expertise is in vivo experimentation. He spearheads the Walk Lab’s germ free and gnotobiotic mouse program, which he and Dr. Walk initiated at MSU in 2012.


Brittany Jenkins – Ph.D. Student

Brittany R. Jenkins

Brittany is interested in the role of microbial metabolites in host gastrointestinal health and disease. Her project focuses on tryptophan-derived indole compounds and how they may ameliorate inflammatory bowel diseases. In addition to using traditional cell culture and murine models to measure intestinal epithelial responses to different indole compounds, her project utilizes a complex tissue culture system called human intestinal organoids (HIOs). HIOs are small, three dimensional spheres of intestinal tissue differentiated from human pluripotent stem cells and represent a novel model system for advancing fundamental and applied biomedical research.


Curriculum vitae for Brittany Jenkins

Research gate link for Brittany Jenkins

Barbara Roggenbeck – Postdoctoral Fellow


Barbara is working to understand the microbiome’s role in detoxifying arsenic and other toxic heavy metals. She is an expert on host cellular uptake mechanisms and is integrating this information with microbial metabolism (redox) of metals.


Qian Wang – Research Assistant Professor


Qian is working to understand the in vivo relevance of microbial metabolisms of arsenic and other toxic metals. She is an expert in molecular biology and is generating mutant bacteria with known microbial metabolisms for gnotobiotic experimentation.


Nicholas Pinkham – Bioinformatician

Nick has an M.S. in Microbiology and joined the Walk Lab to assist with data visualization and analysis. Nick is involved with pretty much every project and contributes to the lab’s growing number of in-house Python and R codes.


Paul van Erp – Postdoctoral Fellow

Paul graduated in 2019 from the Department of Microbiology and Immunology Ph.D. program. He is spearheading our SARS-CoV2 wastewater surveillance program in Gallatin County, MT. Paul’s expertise bacteriophages and bacterial immune response is also a key component of our resident human E. coli project.



Lab Alumni

Jonathan Martinson – Ph.D. (2020)


Jonathan studied antimicrobials that remove plasmids (small non-chromosomal DNA) from bacteria, which often carry antibiotic resistance genes. He also studyied how human intestinal organoids (HIOs) can be used as a model of human intestine.  The primary focus of his dissertation research was the temporal population dynamics of the human microbiome, including members of the Enterobacteriaceae. Jon is currently a postdoc at the University of Minnesota in the lab of William Harcombe.

Ben Dueling – M.S. (2020)


Ben helped develop novel tools to study the molecular cross-talk between mammalian and microbial cells. His project interfaced between cell biology, bioengineering, and microbial ecology with the primary goal of developing a robust microfluidic, culturomics pipeline for identifying the specific micoorganisms that produce bioactive compounds in the mammalian gut. Ben’s interest in mushroom farming eventually got the better of him and he now runs a small business in the Bozeman area that promises to bring premium-grade mushrooms to the leading culinary establishments.

Michael Coryell – Ph.D. (2019)


Mike studied how microbes living in the human gut protect us from exposure to ingested arsenic. His research focused on determining the extent to which the gut microbiome can protect the host from chronic or acute arsenic exposure and what mechanisms underlie this protection. Mike is now a postdoctoral fellow at the FDA in the Center for Biologics Evaluation and Research with Paul Carlson Jr.


Stephanie Schneider – M.S. (2017)


Stephanie is interested in Immunology and host response to infection and disease. She was involved in arsenic detoxification studies in 2015.


Stephen ‘Skip’ Olshefsky – M.S. (2015)


Stephen “Skip” received his MS in Microbiology & Immunology in 2015 and is now pursuing his Ph.D. at the University of Regina (Canada!). His Master’s research was on human intestinal organoids and how Escherichia coli strains could colonize/infect the intestinal epithelium.


Arielle Potter – Undergraduate Researcher (2013-2015)


Arielle received her undergraduate in Microbiology in August of 2015 from MSU. She was part of a variety of projects while in the Walk Lab, but her primary research focus was the characterization of Escherichia strains isolated from the campus duck pond. Arielle received an INBRE-funded undergraduate research scholarship to conduct this research. She is a recent graduate of the Master’s of Public Health Program at Tufts University.

Anna (Andrechak) – Undergraduate Research Assistant (2013-2015)


Anna graduated from MSU in May 2015 with a BS degree in Microbiology, focused on Environmental Health. Anna had a collaborative project with Arielle Potter to look for cryptic Escherichia clades present in the campus duck pond.  Anna received an INBRE scholarship to conduct her research. She collected and processed hundreds (!) of environmental samples and thousands (!) of bacterial isolates for DNA extraction, PCR, and sequencing. After graduation from MSU, she became a Registered Environmental Health Specialist, and obtained a Master’s of Public Health (magna cum laude) from the University of Montana. She didn’t stop there (!), and is currently enrolled in the Montana Medical Laboratory Science Program.

Kaitlyn Okrusch – Undergraduate Researcher (2014-2015)


Kaitlyn finished her BS degree in Nutritional Science and a minor in Biochemistry in May 2015. She has worked in the Walk Lab since May of 2014, with funding from Howard Hughes Medical Institute. Kaitlyn’s project was focused on the ‘hygiene hypothesis’ and Inflammatory Bowel Disease. She is currently working in Bozeman as a Physical Therapist Aide and is involved in an NIH-funded neuroscience project on the MSU campus. She plans to apply for Physician’s Assistant school this coming fall.

Thayne Ekness – Undergraduate Researcher (2016-2017)


Thayne graduated from MSU in 2018 in Chemical and Biological Engineering. His research project in the lab focused on molecular typing of Clostridium difficile strains using PCR ribotyping and multilocus variable tandem number repeat analysis (MLVA). Thayne also conducted antimicrobial susceptibility testing on a number of clinical isolates. Thayne is currently interning at the Pacific Northwest National Laboratory (Sequim, WA), where he is conducting research on algal biofuels.

Trisheena Kills Pretty Enemy – B.S. 2018

Trisheena was an undergraduate researcher in the lab and helped characterize a large set of Clostridioides difficile strains for the presence of toxin genes. She’s currently in the Microbiology Master’s degree program and doing GREAT!


Annie Liotta – Undergraduate Researcher (2014)

Annie received her BS in Microbiology and a minor in Psychology in May of 2015. She is planning to apply for medical school this coming fall.

Christina (Kiki) Johnson – Bioinformatician (2014)

Kiki helped build our PCR ribotyping analysis pipeline and just graduated with her Ph.D. from the Oslo University Hospital. Kiki came back to MSU to postdoc with Dr. Jennifer Dubois in Chemistry and Biochemistry. A joint project between labs brings her around quite often!

Sean Stettner – Undergraduate Researcher (2012-2014)

Sean graduated in May of 2014 with a BS in Chemical and Biological Engineering. He received an NIH INBRE-funded Undergraduate Scholars Program fellowship to conduct research on antibiotic resistant Klebsiella pneumonia. Sean graduated from the Molecular & Cellular Life Ph.D. Program at the University of Wyoming with Naomi Ward and is currently a postdoc in Jeffrey Cameron’s lab at the University of Colorado Boulder.