October 16-17, 2018 | Lincoln, Nebraska
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2018 NRIC speakers
portrait of Mary Firestone


Mary Firestone
University of California, Berkeley
A web of interactions shapes the soil microbiome
Soil microbiomes comprise the most diverse and complex assemblages of organisms on earth reflecting the heterogeneity of their habitat and the array of interactions that shape them.  Introduction of 13Carbon into soil facilitates definition of complex web of biotic interactions through isotope-enabled genomics and genome-resolved metagenomics that reveal phage, bacterial, fungal, and faunal participants; food-web and network modeling identify and quantify guilds.  Resulting data indicate that the development of rhizosphere-competent bacterial consortia support production of “rhizosphere” phage populations. The physical separation of nematodes and protists from soil requires gradient centrifugation and size selection by differential filtration.  DNA extraction and barcode analyses have yielded 50-70% faunal sequences.  Nematode and protist densities have been assessed in bulk and rhizosphere.  Predicted functional roles of these guilds suggest direct root feeding and bacterial and fungal predation. Functional predictions are being evaluated using isotopic methods.
Mary Firestone, Ph.D., is a microbial ecologist who has worked extensively on the roles of soil microorganisms in terrestrial ecosystem function. She is known for her work on nitrogen oxidation and reduction processes, adaptation of microbes to the soil drying, and carbon- and nitrogen-based interactions among plant roots and soil organisms. The extreme heterogeneity of soil and the scale at which microorganisms interact with their habitat has made understanding the ecology of soil microbes a challenge. Her program has brought to bear expertise in microbiology, biogeochemistry, ecosystem science, and community ecology; her work has been recognized by a range of disciplines: she is a fellow of the Soil Science Society of America, American Academy of Microbiology, Ecological Society of America, and American Geophysical Union. Mary was elected to the National Academy of Sciences in 2017.