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 a project examining Clostridium difficile infections from clinical specimens collected at medical centers around the US. This involves testing for the presence of C. difficile using culture, PCR, cell-culture-based cytotoxin assay and an immunoassay. The goal is to determine if any method of diagnosis best determines patient outcome.

Phone: 406-994-1744


Mark McAlpine – Lab Animal Manager


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


Michael Coryell – Ph.D. Student


Michael is studying how microbes living in the human gut protect us from exposure to ingested arsenic. His research focuses 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.


Jonathan Martinson – PhD Student


Jonathan is studying antimicrobials that remove plasmids (small non-chromosomal DNA), which often carry antibiotic resistance genes. He is also studying how human intestinal organoids (HIOs) can be used as a model of the human intestine.  The primary focus of his dissertation research is temporal population dynamics of the human microbiome.



Brittany Jenkins – PhD 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

Ben Dueling – PhD student


Ben is interested in developing novel tools to study the molecular cross-talk between mammalian and microbial cells. His project interfaces 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.



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 – Postdoctoral Fellow


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.






Lab Alumni

Stephanie Schneider – Rotation Student (2015)


Stephanie is interested in Immunology and host response to infection and disease. She is a Ph.D. student in the Department of Microbiology & Immunology at MSU and was involved in arsenic detoxification studies in 2015.


Stephen ‘Skip’ Olshefsky – Masters Student (2013-2015)


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 currently enrolled in the Master’s of Public Health 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 – Undergraduate Researcher


Trisheena is a Junior in Microbiology with a focus on Medical Laboratory Sciences. Trisheena has characterized a large set of Clostridium difficile strains for the presence of toxin genes.





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 currently a PhD student at the Oslo University Hospital.

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 is now in the Molecular & Cellular Life PhD Program at the University of Wyoming under the mentorship of Dr. Naomi Ward.