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An invisible ecosystem of checks and balances exists within our bodies. But what happens when disease throws a wrench in these works? 

Distinguished Professor Andreas Bäumler is a leader in the study of microbial physiology. He is particularly known for his holistic research on the role of the host’s environment and the microbial composition of an organ, specifically the gut’s microbiota.

Bäumler is the vice chair of research in the Department of Medical Microbiology and Immunology at the School of Medicine. He received his Ph.D. in microbiology from the University of Tübingen, in Germany, in 1992 before serving as a postdoctoral fellow at the Oregon Health Sciences University, where he first analyzed salmonella’s role in infecting the intestines. He joined �������� in 2005 and was elected to the National Academy of Sciences in 2023.

The epithelium, the body tissue lining the exterior and interior of organs like our gut, shelters the gut’s beneficial bacteria from oxygen, helping that bacteria perform tasks like digesting our food. Bäumler’s research demonstrated the role the host plays when its gut’s collective microorganisms, known as its microbiota composition, are altered when oxygen seeps through the epithelium into the cavity of the gut.  

“These bacteria that bloom when oxygen is present make certain molecules that can escalate the production of uremic toxins,” he said. “And that can exacerbate progression of cardiovascular disease and chronic kidney disease.”

Bäumler used animal modeling to study salmonella infection and how the disease uses its virulence factors to target a host’s organs like the gut. Understanding these ecological changes in the microbiota composition is a key first step for identifying clinical interventions. 

“Every disease has a different negative outcome, but they all have in common that you first have a loss of control over the gut community,” Bäumler explained.

By identifying the factors affecting gut homeostasis, Bäumler’s research strategies could be applied across an array of different diseases each with their own unique challenges. 

“All these conditions that have changes in the microbiota composition share a common driver, because when oxygen is present, other bacteria will be more successful.” Bäumler explained, noting the gut’s role in maintaining homeostasis. 

When Bäumler arrived at Davis 20 years ago, he found “a very collaborative environment that was always very helpful.” 

Bäumler and others worked with the School of Medicine to create a sterile facility to further their research.

“It was important to have germ-free mice,” Bäumler said, explaining that it allowed him to examine the mice’s gut microbiota in an environment free of microorganisms. “That was instrumental; to go into this direction, it sometimes requires new technology.” Bäumler also utilizes the Genome Center's core facilities and tools for analysis across the molecular biological field. 

Bäumler also cites the unique “quality of students and postdocs” at Davis.

“I had fantastic cohorts of trainees going through my lab, who lifted my program up.”