Congratulations to Brianne Zbylicki for passing her PhD defense on October 30, 2025. She is pictured with her mentor, Craig Ellermeier, PhD. Her thesis is titled, "Biogenesis of the Clostridioides difficile Membrane: Glycolipid and Lipoteichoic Acid Synthesis".
Research
Clostridioides difficile is the most common cause of healthcare-associated diarrhea, and the CDC has classified C. difficile infections as an urgent public health threat requiring urgent and aggressive action. Development of new narrow-spectrum therapeutics is needed to better treat C. difficile infections. The Ellermeier lab studies the biogenesis of the atypical C. difficile cell envelope to discover new targets for therapeutics to selectively inhibit C. difficile.
The membrane of C. difficile contains a high proportion (~50%) of glycolipids compared to other organisms. I identified the glycosyltransferases, UgtA and UgtB, which are required for glycolipid synthesis in C. difficile, and that glycolipids are important for viability, normal cell morphology, sporulation, and maintaining membrane fluidity.
Lipoteichoic acid (LTA) is an extracellular polymer that is important for viability, maintenance of cell morphology, and cell division in other Gram-positive bacteria. C. difficile produces an uncommon LTA structure that contains a polysaccharide of repeating units of GlcNAc-GlcNAc-GroA, joined by rare 6-P-6 phosphodiester linkages, anchored in the membrane by a glycolipid. I identified two proteins, LtaA and LtaB, which are novel LTA synthases that are important for LTA synthesis. Loss of LtaA and LtaB leads to severe growth defects, morphological defects, aberrant division septa placement, and cell lysis.
Taken together, these findings reveal that the unique glycolipid and LTA biosynthetic pathways in C. difficile are critical for cell survival and may represent promising targets for developing narrow-spectrum therapeutics.
Background
Brianne was born and raised in West Des Moines, Iowa to Lisa and Steve Zbylicki. From a young age her curiosity in the world around her was evident by her desire to learn “fun facts” and to share them with anyone who would listen, especially her family at the dinner table. Brianne became interested in understanding organisms and their environments during her biology classes in high school.
Brianne attended the University of Portland in Oregon for her undergraduate studies. In a microbiology lecture and lab taught by Ryan Kenton “Dr. K,” Brianne became fascinated by microbes and their complexity. She participated in undergraduate research in Dr. K’s lab studying iron acquisition and antibiotic resistance in the “flesh-eating” bacteria Vibrio vulnificus.
In 2020, Brianne joined the department of Microbiology and Immunology at the University of Iowa and joined the lab of Craig Ellermeier. Here she has grown fond of the challenge of working on the obligate anaerobe, Clostridioides difficile, including the creative problem-solving and planning it takes to perform experiments inside an anaerobic chamber. Her research in the Ellermeier lab has resulted in two first-author publications, with a third one on the way. After graduation, Brianne will be pursuing a career in public health starting with a fellowship through the Association of Public Health Laboratories to work at the State Hygienic Lab here at the University of Iowa.
After graduation, Brianne is looking forward to marrying her fiancé and long-time supporter, David. While at Iowa, Brianne has greatly enjoyed playing D&D with David and her brother and sister-in-law, Nathan and Lisa, with the help of their sidekick and squire, her nephew George. After long day in lab, Brianne loves cozying up with a good book and a cup of tea or a glass of wine. To help keep her sanity during her PhD, Brianne has greatly enjoyed her hobbies of sewing, reading, gardening, jigsaw puzzles, embroidery, and playing video and board games with friends and family.