Abstract
The aquatic communities found within the water filled leaves of the pitcher plant, Sarracenia purpurea, have a simple trophic structure providing an ideal system to study microscale interactions between protozoan predators and their bacterial prey. In this study, replicate communities were maintained with and without the presence of the bactivorous protozoan, Colpoda steinii, to determine the effects of grazing on microbial communities. Changes in microbial (Archaea and Bacteria) community structure were assessed using iTag sequencing of 16S rRNA genes. The microbial communities were similar with and without the protozoan predator, with>1000 species. Of these species, Archaea were negligible, with Bacteria comprising 99.99% of the microbial community. The Proteobacteria and Bacteroidetes were the most dominant phyla. The addition of a protozoan predator did not have a significant effect on microbial evenness nor richness. However, the presence of the protozoan did cause a significant shift in the relative abundances of a number of bacterial species. This suggested that bactivorous protozoan may target specific bacterial species and/or that certain bacterial species have innate mechanisms by which they evade predators. These findings help to elucidate the effect that trophic structure perturbations have on predator prey interactions in microbial systems.
Highlights
The effect of predators on the prey community is a well-studied area of ecology (e.g., [1])
The goal of this study was to determine the predator-prey effects of the protozoan, C. steinii, on the microbial community in S. purpurea pitcher fluids. While grazing by this protozoan in S. purpurea pitcher fluids resulted in statistically significant shifts in the relative abundance of 42 bacterial species, there was no change in overall microbial community richness or diversity
Of these 42 species, those that had a statistically higher relative abundance without C. steinii present were generally closely related to motile, planktonic species, leading us to hypothesize that, in our experiments, protozoa targeted microorganisms residing in the pitcher fluids, rather than those associated with particles, such as soil
Summary
The effect of predators on the prey community is a well-studied area of ecology (e.g., [1]). Predators generally reduce the abundance of prey, which can, in turn, affect the abundance of predators and result in oscillations between predator and prey. Little is known about the effects of predators on microbial communities [2, 3]. The rich diversity of microorganisms creates methodological challenges, rendering it difficult to predict overall effects of predation on microbial community structure. It is unknown if standard ecological predictions of predator-prey dynamics and effects of predators on prey community composition will apply in highly speciose microbial communities [4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
