Thermal performance analysis of bacteria and bacterivore interactions

Abstract

Microbiomes have a significant role in global carbon emissions and can potentially shift in response to climate change. Bacterivores play a strong role in regulating soil biomes and therefore could alter the structure of these microbial communities if theywere impacted by a slight change in temperature. We hope to estimate how bacterivores and their prey could shift in their relationships in the presence of one another across a thermal gradient. We cultured the bacterivore protist Paramecium aurelia on 3 bacterial treatments (E. Coli, S. enteritidis, and their combination). We then subjected each combined P. aurelia and bacterial treatment to a 12-37°C gradient of temperatures for 18-24 hours under exponential growth conditions. Each bacterial treatment was divided into a bacteria control, and 2 P. aurelia + bacteria plates (one for counting protists, one for measuring the effects of protists on bacteria) and replicated 5 times across 8 temperatures. Paramecium were counted individually after being pipetted and bacterial counts were conducted by hemocytometer. We predict inherent differences in temperature-dependent bacterial growth rates will have cascading impacts on the fitness of their predators. We also predict that differences in the number of bacterial cells in suspension versus in biofilms will affect the growth rates of Paramecium. The outcomes of this project will be critical first steps for elucidating the joint impacts of shifting climates and bacterivore communities on microbiomes.