At Calvin Professor Wertz teaches the Phage Research course, Microbiology, and Medical Microbiology. Others areas of scholarly interest include the history of science, and how disease epidemics have shaped world history.

While not at Calvin, he enjoys spending time outdoors with his family, boating, swimming, biking, and hiking. An avid music lover, he is often found at various concerts around Grand Rapids or dancing (badly) to music in his office.


  • B.S. in Biology, Calvin College, 2001
  • Ph.D. in Microbiology, Michigan State University, 2006

Professional Experience

After graduating from Calvin College in 2001, John went to Michigan State University to complete a Ph.D. in Microbiology, there he focused on the sub-field of microbial ecology. After completion of his Ph.D., he went on to a postdoctoral position, also at Michigan State, doing research in a developing (as-yet-unnamed) field where microbial ecology meets medical microbiology. As part of his postdoctoral experience, he jumped at the opportunity to teach an introductory biology course for biology majors, which consisted of a class size of 250 students. Jumping away from such large class sizes (among other things), he sought refuge back at Calvin where he has been teaching since 2007.

Courses taught


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Academic Interests

Research and Professional Interests

Dr Wertz's research interests include investigating bacterial symbioses within complex ecosystems. He is particularly interested in the phenomenon of microaerophily in bacteria, the detection and cultivation of novel bacterial diversity, and the biochemical basis for microbe-microbe and host-microbe symbioses. As a model, he uses the termite gut, which consists of as many as 700 different species of bacteria that interact in a complex web with each other and with the termite host. He has been successful in isolating several novel bacteria from this ecosystem, which he continues to study and be surprised by their intricate complexity. He has also been able to take the lessons learned from studying the bacterial symbionts in termite guts and apply that to the human microbial community. He has collaborated with Dr. Amy Wilsterman at Calvin and Dr. Terry Marsh at MSU, investigating human bacterial community dynamics and the connection to pre-term birth. He also continues to collaborate with Dr. Tom Schmidt at MSU answering questions about novel members of the bacterial phylum Verrucomicrobia as well as efforts to cultivate and study how the human intestinal microbiota contributes to health and disease, particularly with Irritable Bowel Syndrome. 

Selected publications