Bottom-up effects of bacteria on protozoan consumers
Like other pitcher plant species, Sarracenia purpurea live in soils that are relatively poor in nutrients. To compensate for low nutrients they are carnivorousCarnivorous plants are plants that derive some or most of their nutrients (but not energy) from trapping and consuming animals or protozoans, typically insects and other arthropods. The insects crawl into the pitchers and become trapped in a pool of rainwater and then are broken down by a community of bacteria. These bacteria are consumed by protozoa in the genus Tetrahymena. The protists are then consumed by mosquito larvae.
My first experiment with this system was designed to test the bottom-up effects of bacteria on the protists. I wanted to determine if all bacteria are the same for the protists or if some bacteria are better for protist growth. We found that it does make a difference. Some strains help the protists to multiply quickly, while others kill all the protists in the sample. We also combined different bacterial strains together to create "good communities" and "bad communities" and found that the effect of bacteria on protists fitness persists when the bacteria are in a community.