CAREER: Impact of elemental limitation on the evolution and composition of bacteria

All organisms consist of a mixture of elements in differing ratios. Elements such as carbon, nitrogen, and phosphorus are needed to make the nucleic acids, proteins and other molecules that are the building blocks of cells. However, the availability of these elements in organisms’ environments often differs from the proportions needed by organisms. As a result, the availability of the scarcest element can limit growth. This project will explore how bacteria evolve in response to the scarcity of different elements. Bacteria will evolve under controlled laboratory conditions with varying ratios of carbon, nitrogen, and phosphorus. The researchers will measure elemental composition, genetic changes, and fitness of the evolved bacteria. Human activity has altered elemental availability across a variety of habitats, including addition of nitrogen and phosphorus as fertilizer. The research in this project will help lay the foundation for understanding how organisms may evolve in response to changes in elemental availability. This project will also provide research experiences for community college students who will conduct an evolution experiment as part of their introductory biology laboratory course and then have the opportunity to contribute to the project as undergraduate researchers. This project will address how the elemental composition of bacteria evolves in response to elemental limitation. The researchers will test whether selection under elemental limitation favors a nutrient sparing response in which bacteria evolve to incorporate less of the limiting element in their cells. The evolutionary response to elemental limitation may also depend on other aspects of the environment. This research will test the role of differing selection pressures by comparing the outcome of evolution under selection for faster growth rate and evolution under selection for increased yield. Response to limitation may also depend on the starting characteristics of the organisms. To explore this, the researchers will also test the role of genetic background on the evolutionary response to limitation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2543968 | Program: 01003031DB NSF RESEARCH & RELATED ACTIVIT,01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Caroline Turner | Institution: Loyola University of Chicago, CHICAGO, IL | Award Amount: $775,664 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2543968 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2543968.html