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Browsing Theses and Dissertations by Author "Alster, Charlotte J., author"

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    Temperature sensitivity as a microbial trait
    (Colorado State University. Libraries, 2017) Alster, Charlotte J., author; von Fischer, Joseph, advisor; Cotrufo, Francesca, committee member; Smith, Melinda, committee member; Wallenstein, Matthew, committee member
    Reaction rates in biological systems are strongly controlled by temperature, yet the degree to which temperature sensitivity varies for different enzymes and microorganisms is being largely reformulated. The Arrhenius equation is the most commonly used model over the last century that predicts reaction rate response with temperature. However, the Arrhenius equation does not account for large heat capacities associated with enzymes in biological reactions, thus creating significant deviations from predicted reaction rates. A relatively new model, Macromolecular Rate Theory (MMRT), modifies the Arrhenius equation by accounting for the temperature dependence of these large heat capacities found in biological reactions. Using the MMRT model I have developed a novel framework to assess temperature sensitivity as a biological trait through a series of experiments. This work provides evidence that microbes and enzymes can have distinct heat capacities, and thus distinct temperature sensitivities, independent of their external environment. I first assessed temperature sensitivity of soil CO2 production from different soil microbial communities and then worked with pure cultures to examine temperature sensitivity of enzyme activities from soil microbial isolates. From these experiments I determined that temperature sensitivity varies based on genetic variation of the microbe and substrate type as well as examined the importance of using MMRT over the Arrhenius equation. Finally, I used a meta-analysis to analyze the distribution of temperature sensitivity traits to look across a variety of biological systems (e.g., the food industry, wastewater treatment, soils). I found that temperature sensitivity traits vary with organism type, environment, process type, and biodiversity. Exploring temperature sensitivity as a trait allows for new insights of soil microbes from an ecological perspective as well has the potential to inform ecosystem climate models.