2026 Undergraduate Research Showcase

Not Just Waste: The Negative Effects of Chromobacterium Spent Media on Tetrahymena

Document Type

Student Presentation

Presentation Date

4-24-2026

Faculty Sponsor

Dr. Leonora Bittleston and Fiona Harrigian

Abstract

Microbial communities have similar predator-prey interactions as seen in larger organisms. Predators are widely known to hunt and kill their prey, yet we know less about prey antagonism towards the predator. For example, there are intricate interactions between protozoa and bacteria that take place within the aquatic pools of a carnivorous pitcher plant, Sarracenia purpurea. Specifically, the interactions between the protozoan, Tetrahymena, the beneficial bacterium, Pedobacter, and the harmful bacterium, Chromobacterium. To better understand how Chromobacterium harms Tetrahymena, we measured the effects of Chromobacterium spent media on Tetrahymena to determine if it is releasing toxic metabolites. Unfortunately, it can be difficult to isolate Tetrahymena from the bacteria it consumes, and a contaminant was introduced to the experiment. However, we can still analyze our results by comparing specific treatments. When analyzing Tetrahymena cell density, the trend matches our previous findings showing Pedobacter supporting high Tetrahymena cell density and Chromobacterium supporting only very low Tetrahymena cell density. Chromobacterium spent media showed a decrease in Tetrahymena cell density throughout all treatments even under favorable conditions. This suggests that there is a toxic metabolite excreted by the bacterium. The findings have implications for not only microbial interactions, but also for understanding how predator-prey interactions dynamically shape community structures.

This document is currently not available here.

Share

COinS