Deciphering the predator-prey dynamics between protists and bacterial biofilms

Bacteria and protists represent two of the largest contributors to biomass in ocean ecosystems, thus they influence major geochemical cycles such as carbon cycling and constitute an important sector of the marine food web. However, the nature of bacteria-protist interactions, specifically in the context of bacterial biofilms, has been unexplored with at most empirical or qualitative insight. Here, we address this gap in knowledge using the model biofilm-forming species Vibrio cholerae and the ciliate protist Tetrahymena pyriformis. Preliminary results indicate that a biofilm’s size and extracellular matrix serve as the primary defenses against protist grazing suggesting that a biofilm’s physical properties strongly influence the ecological outcomes between protists and bacteria. Through these quantitative experiments, we can start developing a mechanistic framework for understanding bacteria-protist interactions and their implications for microbial ecology and biogeochemical cycling in aquatic environments.