Our research focuses on the role and impact of commensal protists in the gut microbiota.

Our gut microbiomes, the constellations on microorganisms that live inside our intestinal tracts, have a dramatic and dynamic impact on our health and disease status. However, while most research on the gut microbiome focuses on the bacterial members, this diverse community is also made up of archaea, viruses, fungi, and even protists. Protists, single-celled microeukaryotes, are the least well understood component of the gut microbiota but play a crucial role in these communities. In particular, a specific group of protists, the parabasalids, have a dramatic impact on the intestinal environment. These enigmatic commensals can completely remodel the intestinal immune response in both the small and large intestine, which alters the host’s susceptibility to both infectious and inflammatory diseases. Thus, despite being ignored in the majority of microbiome studies, protists are key players in the microbiome ecosystem and impart an outsized role on the host.

Our goal is to use cutting edge techniques to investigate the mechanisms by which commensal parabasalids act as architects of the intestinal ecosystem. Some of our current interests therefore include:

1) Diversity of commensal parabasalids. We previously discovered a new species of murine commensal parabasalid, Tritrichomonas casperi, which has illuminated important aspects of the biology and effects of these protists. We are therefore keenly interested in studying diverse parabasalids in the gut microbiota in order to expand this knowledge.

2) Trans-kingdom interactions in the gut microbiota. Although parabasalids are key members of the microbiota, they must share this ecosystem with other microbes. Our previous work has uncovered intricate interactions between commensal parabasalids and the bacterial members of the gut microbiota. We are interested in mechanistically dissecting these interactions and the effects they have on the host.

3) Commensal parabasalid metabolism. The gut microbiota encodes massive metabolic capacity, the products of which signal to both the host and the microbiota to modulate their activity. Parabasalid metabolism in particular can completely remodel the intestinal immune landscape, and we are therefore interested in understanding the metabolism of these protists and how it impacts the intestine.

4) Tools in commensal parabasalids. We previously discovered how to culture the prominent commensal parabasalid, Tritrichomonas musculis, in vitro (Gerrick et al, Cell 2024). This basic capability enabled key discoveries about how these protists function in the microbiota, and paves the way for the development of more advanced tools including CRISPR.