Professor, Associate Dean of Instruction & Student Affairs
Ph.D. Soil Microbiology Michigan State University, 1979
Soil microbial ecology: Microbial processing of carbon and nitrogen underlie the capacity of soil to support plant growth in agriculture, rangeland, forests, and wetlands. However 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 of long duration. The research done in the Firestone lab aspires to fundamental understanding as well as knowledge applicable to current problems including terrestrial system response to global change, sustainability, biodegradation, and soil structure. Current research interests include:
- Interactions of bacteria with the soil environment. How does the physical/chemical characteristics of the microhabitat determine growth and activity of soil microbes. Do indigenous soil microbes alter the characteristics of their microhabitats through the production of extracellular polysaccharides matrices? We have learned that:
- Bacteria indigenous to surface soils are highly adapted (physiologically and ecologically) to soil water potential fluctuations
- The polysaccharide matrices surrounding bacterial cells in soil control rates of wetting and drying of the bacterial microhabitat
- Soil water potential and content impact rates of soil microbial processes through diffusional control of solution phase substrate supply as well as control of physiological processes.
- High amplitude fluctuations in soil redox status in upland wet tropical rain forest soils promote the occurrence of very-low-redox N and C processes.
- Diffusion-limited mesoscale domains in soil aggregates create habitats for growth and activity of bacteria capable of low redox metabolic processes
- Microbial community ecology of N and C cycling. How does the composition of soil microbial communities control soil N and C transformations including nitrification, denitrification, organic-N mineralization, and production of atmospherically reactive gases. How do differences in the microbial community composition between soils translate into differing soil process rates? We have learned that:
- The composition of the microbial community (as defined by DNR, RNA and PLFA fingerprinting) can be related to enzyme activity in tropical soils as well as soil C and N transformations in California soils
- The response of terrestrial ecosystems to environmental change will be determined in part by the impacts of the changing environment on soil microbial communities.
- The spatial distribution of bacterial communities in aggregates connect redox potential to metal reduction.
- Mechanisms of interaction between plant roots and soil microorganisms. How does the spatially and temporally complex interchange of C and N between plant roots and soil microorganisms control plant-N availability, soil carbon dynamics, and pollutant biodegradation. We have recently earned that:
- The patterns of exudates along plant roots are spatially complex and differ among small molecular weight compounds. Root patterns control bacterial and protozoal numbers as well as N-dynamics
- Nitrogen-mineralization is 10x higher in rhizosphere soil and nitrification is controlled primarily by root consumption of ammonium.
- Root-microbial interactions underlie terrestrial ecosystem response to elevated CO2 and atmospheric N-deposition.
- Root enhancement of PAH degradation is compound specific, involving selective stimulation of degrading communities by root exudate materials.
Herman, D., M, Firestone, E. Nuccio, A. Hodge. 2012. Interactions between an arbuscular mycorrhizal fungus and a soil microbial community mediating litter decomposition. FEMS Microbiology Ecology. FEMS Microbiology Ecology. 80:236-247.
DeAngelis, K. and M. Firestone. 2012. Phylogenetic clustering of soil microbial communities in 16S rRNA but not 16S rRNA genes. Applied and Environmental Microbiol. 78(7): 2459.
Blazewicz, S.J., D.G. Petersen, M.P. Waldrop, and M.K. Firestone. 2012. Anaerobic Oxidation of Methane in Tropical and Boreal Soils: Ecological Significance in Terrestrial Methane Cycling. J. Geophysical Res. Biogeosciences (In Press).
Placella, S.A., E.L, Brodie, and M.K. Firestone. 2012. Rainfall induced carbon dioxide pulses result from sequential resuscitation of phylogenetically clustered microbial groups. PNAS. 109:10931-10936.
Throckmorton, H.M., J.A. Bird, L. Dane, M.K. Firestone, and W.R. Horwath. 2012. The source of microbial C has little impact on soil organic matter stabilization in forest ecosystems. Ecology Lett. Doi:10.1111/j.1461-0248.2012.01848x
Peterson, D. G., S. Blazewicz, D. J. Herman, M. Firestone, M. Turetsky, and M. Waldrop. 2012. Abundance of microbial genes associated with nitrogen cycling as indices of biogeochemical process rates across a vegetation gradient in Alaska. Environmental Microbiology 14: 993–1008
Bird, J.A., D.J. Herman and M.K. Firestone. 2011. Rhizosphere priming of soil organic matter by bacterial groups in a grassland soil. Soil Biology and Biochemistry 43:718-725.
Dubinsky, Eric A., Whendee L. Silver, and Mary K. Firestone. 2010. Tropical forest soil microbial communities couple iron and carbon biogeochemistry. Ecology 91:2604-2612.
DeAngelis, K.M. W.L. Silver, A.W. Thopson, and M.K. Firestone. 2010. Microbial communities acclimate to recurring changes in soil redox potential status. Environ. Microbiol. 12:3137-3149.
DeAngelis, K,.S. Lindow, M. Firestone. 2008. Bacterial quorum sensing and nitrogen cycling in rhizosphere soil. FEMS Microb Ecol. 66:197-207.
Hawkes, C.V., K. DeAngelis, and M.K. Firestone. 2007. Root interactions with soil micbial communities and processes. In Z. Cardon and J. Whitbeck eds., The Rhizosphere an Ecological Perspective. pp. 1-31. Elsevier, New York.
James I Prosser, Brendan JM Bohannan, Tom P Curtis, Richard J Ellis, Mary K Firestone, Rob P Freckleton, Jessica L Green, Laura E Green, Ken Killham, Jack J Lennon, A Mark Osborn, Martin Solan, Christopher J van der Gast, J Peter W Young. 2007. The Role of Ecological Theory in Microbial Ecology. Nature Microbiology.
Honors and Awards
- Berkeley Faculty Service Award 2011-12. UC Berkeley Academic Senate.
- Senior Fulbright Fellow, Lincoln University, New Zealand – Nov-Dec 2007.
- Eminent Ecologist in Residence, W.K. Kellogg Biological Station, MI, July 1997 & 2007.
- Clark Distinguished Lecturer, Soil Science Society Meetings, Seattle – 2004
- BBSRC Underwood Fellow, York University, UK 2004-05
- Brown & Williamson Distinguished Lecturer, University of Louisville – 2003
- Distinguished Environmental Scientist, Woods Hole – 2002
- Fellow - American Academy of Microbiology – 2002
- Distinguished Scientist, Institute for Ecosystem Studies, N.Y. -1999
- Fellow - Soil Science Society of America - 1995
- ES 10 - ENVIRONMENTAL SCIENCE
- ESPM 131 - MICROBIAL ECOLOGY
- 199 - SUPERV INDEP STUDY
- 299 - INDIVIDUAL RESEARCH
Office: 333 Hilgard Hall, 32 Hilgard Hall
Office Phone: 510-642-3677
Lab Phone: 510-642-6847
Fall Semester 2012
On sabbatical off campus
Department of Environmental Science Policy and Management
132 Mulford Hall
University of California
Berkeley, CA 94720