Ashley Weiss (she/her)

Enterococcus faecalis modulates phase variation in Clostridioides difficile | Journal of Bacteriology Clostridioides difficile is an enteric pathogen with critical implications for public health. The microbial ecosystem in which C. difficile resides shapes the behavior and fitness of C. difficile; however, the mechanisms underlying these interactions are not well defined. Here, we demonstrate that Enterococcus faecalis, an opportunistic pathogen known to co-colonize the gut with C. difficile, influences phase variation and downstream growth phenotypes in C. difficile. This phenomenon represents a new paradigm by which co-residing bacteria can modulate phase variation dynamics in C. difficile or other enteric pathogens. Understanding factors that influence C. difficile behavior may elucidate new therapeutic strategies, especially in complex polymicrobial infections.

Excited to share my publication, showing that co-residing bacteria in the gut alters population heterogeneity in C. difficile. Thank you to my co-author, Jilarie Santos-Santiago, and our collaborative team from the labs of @joeyzacks.bsky.social and @ritatamayo.bsky.social! 
doi.org/10.1128/jb.0...

Last week, I presented my research at ClostPath 2025 at the Pasteur Institute in Paris. It was wonderful to share my work on polymicrobial interactions in the gut microbiome and hear from others also studying Clostridial pathogens. Thank you to the conference organizers for this amazing opportunity!

I’m excited to share my recent study from the labs of @joeyzacks.bsky.social and @ritatamayo.bsky.social on the impact of E.faecalis on phase variable behaviors in C.difficile. This work was achieved through amazing co-leadership with PhD candidate Jilarie Santos-Santiago.

Thanks so much, Joe!

I am honored to be offered an award for the 2024 National Science Foundation (NSF) Graduate Research Fellowship Program (GRFP) in microbial biology. I am excited to utilize support from this award to continue my thesis work and advance my scientific career during graduate school!

Thank you Joe! So excited!

BilR is a gut microbial enzyme that reduces bilirubin to urobilinogen - Nature Microbiology BilR is identified as a bilirubin reductase encoded by gut bacteria, which reduces bilirubin to urobilinogen.

I’m so excited to see my undergraduate lab’s work published in #NatureMicrobiology ! It was a pleasure to work on this project with Dr. Brantley Hall and Dr. Xiaofang Xiang, and congratulations to the entire team! www.nature.com/articles/s41...