Collaborative Research: Do expected evolutionary trade-offs in enzyme activities manifest at the level of microbial community function?

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Respiration is the process by which chemical energy is released in a series of enzyme-catalyzed steps typically involving the consumption of organic (carbon containing) compounds and oxygen, and the production of carbon dioxide and water. The speed at which respiration occurs, and carbon dioxide is produced, increases as temperatures increase. For this reason there is concern that microorganisms living in soil, where much of the world's carbon is stored, will consume more soil carbon under global warming. If they do, they may release more carbon dioxide into the atmosphere, potentially accelerating global warming. There is substantial uncertainty as to whether this positive feedback to warming will happen - in part because living things can produce respiratory enzymes that have different temperature sensitivities. The goal of this project is to test whether soil microbes maintain initial increases in respiration when temperatures rise, or whether over time they decrease respiration in a way that is consistent with production of less temperature-sensitive enzymes. To quantify soil microbes, this 3-year project will use DNA-sequencing and fatty-acid profiling methodologies. To determine respiration rates, carbon dioxide production from soils will be measured using gas-analysis techniques. To generate differences in temperatures to which microbes are exposed, soils will be collected across a gradient from the arctic to the tropics, in winter and in summer, and incubated in the laboratory at different temperatures.Results of this project will be important because they will help improve predictions of soil microbial responses and feedbacks to future climate changes, facilitating development of management strategies to mitigate impacts of global warming on humans and ecosystems. From the perspective of basic science, it will help scientists determine whether responses inside microbial cells can alter ecosystem processes that influence the climate system. From education and training perspectives, the project solidifies collaborations between three assistant professors in schools within the U.S. The professors will train the next generation of U.S scientists by advising undergraduate students in conducting independent research. Furthermore, doctoral students will be trained through an interdisciplinary workshop integrating microbiology and ecosystem science. As microbes are the engines that drive the biogeochemical processes on which life depends, this integration is important to help guide sustainable management of the planet.