Brad Bebout

Contact Information
Title: 
Research Scientist
Phone: 
(650)604-3227
Email : 
Brad.M.Bebout@nasa.gov
Professional Background
Professional Biography: 
1997-Present Research Scientist, Exobiology Branch, NASA Ames Research Center, Moffett Field, California
1995-1997 Horn Point Environmental Laboratory Post-doctoral Fellow, Horn Point Environmental Lab, Cambridge, Maryland
1992-1995 Post-doctoral Researcher, Microsensor Group, Max Planck Institute for Marine Microbiology, Bremen, Germany
1988-1992 Research Assistant, Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, NC
Bio: 
I am interested in the way that various elements, but principally nitrogen, are cycled in microbial mat and stromatolite communities. Microbial mats are often found in extremely nutrient poor environments. I am interested in knowing the ways in which nitrogen is obtained by mat microorganisms in these nutrient-poor environments. In addition, I am measuring the production and consumption of trace gases in microbial mats and stromatolites. The detection, and interpretation of biogenicity of "biomarker" gases (particularly methane) is very important in our search for life on Mars and even on extrasolar planets. We need to know more about the way in which microbial communities affect atmospheric levels of these trace gases.
Education: 
1983 B.A. in Biology, University of California, Santa Cruz
1988 M.S. in Marine Sciences, University of North Carolina at Chapel Hill
1992 Ph.D. in Marine Sciences, University of North Carolina at Chapel Hill
Research Interests: 
I am interested in the way that various elements, but principally nitrogen, are cycled in microbial mat and stromatolite communities. Microbial mats are often found in extremely nutrient poor environments. I am interested in knowing the ways in which nitrogen is obtained by mat microorganisms in these nutrient-poor environments. In addition, I am measuring the production and consumption of trace gases in microbial mats and stromatolites. The detection, and interpretation of biogenicity of "biomarker" gases (particularly methane) is very important in our search for life on Mars and even on extrasolar planets. We need to know more about the way in which microbial communities affect atmospheric levels of these trace gases.
Select Publications: 
Dillon J.G., S.R. Miller, B.M. Bebout, M. Hullar, N. Pinel, D.A. Stahl 2009. Spatial and Temporal Variability in a Stratified Hypersaline Microbial Mat Community. FEMS Microbiology Ecology 68:46-58.

Potter, E.G., B.M. Bebout, and C Kelley 2009. Isotopic Composition of Methane and Inferred Methanogenic Substrates Along a Salinity Gradient in a Hypersaline Microbial Mat System. Astrobiology 9:383-390.

Kunin, V., J. Raes, J. K. Harris, J. R. Spear, J. J. Walker, N. Ivanova, C. von Mering, B. M. Bebout, N. R. Pace, P. Bork, and P. Hugenholtz. 2008. Millimeter-scale genetic gradients and community-level molecular convergence in a hypersaline microbial mat. Molecular Systems Biology 4:198.

Smith, J. M., S. J. Green, C. A. Kelley, L. E. Prufert-Bebout, and B. M. Bebout. 2008. Shifts in methanogenic community structure and function associated with long-term manipulation of sulfate and salinity in a hypersaline microbial mat. Environmental Microbiology 10:386-394.

Dillon J. G., S. Fishbain, S. R. Miller, B. M. Bebout, K. S. Habicht, S. M. Webb, and D. A. Stahl. 2007. High rates of sulfate reduction in a low-sulfate hot spring microbial mat are driven by a low level of diversity of sulfate-respiring microorganisms. Applied and Environmental Microbiology 73:5218–5226.

Fleming, E. D., B. M. Bebout, and R. W. Castenholz. 2007. Effects of salinity and light intensity on the resumption of photosynthesis in rehydrated cyanobacterial mat from Baja California Sur, Mexico. Journal of Phycology 43:15-24.

Kelley, C. A., L. E. Bebout, and B. M. Bebout. 2006. Changes in carbon cycling ascertained by stable isotopic analyses in a hypersaline microbial mat. Journal of Geophysical Research-Biogeosciences 111:G04012.

Moisander, P. H., L. Shiue, G. F. Steward, B. D. Jenkins, B. M. Bebout, and J. P. Zehr. 2006. Application of a nifH oligonucleotide microarray for profiling diversity of N2-fixing microorganisms in marine microbial mats. Environmental Microbiology 8: 1721-1735.

Ley, R.E., J. K. Harris, J. Wilcox, J. R. Spear, S. R. Miller, B M. Bebout, J. A. Maresca, D. A. Bryant and N. R. Pace. 2006. Unexpected diversity and complexity from the Guerrero Negro hypersaline microbial mat. Applied and Environmental Microbiology 72:3685-3695.

Decker, K. L. M., C. S. Potter, B. M. Bebout, D. J. Des Marais, S. Carpenter, M. Discipulo, T. Hoehler, S. R. Miller, B. Thamdrup, K. Turk, and P. T. Visscher. 2005. Mathematical simulation of the diel O, S, and C biogeochemistry of a hypersaline microbial mat. FEMS Microbiology Ecology 52: 377-395.

Bebout, B. M., T. M. Hoehler, B. Thamdrup, D. Albert, S. P. Carpenter, K. Turk, M. Hogan, and D. J. Des Marais. 2004. Methane production by microbial mats under low sulfate concentrations. Geobiology 2: 87-96.

Miller, S. R., and B. M. Bebout. 2004. Variation in sulfide tolerance of photosystem II in phylogenetically diverse cyanobacteria from sulfidic habitats. Applied and Environmental Microbiology 70: 736-744.

Omoregie, E. O., L. L. Crumbliss, B. M. Bebout, and J. P. Zehr. 2004. Comparison of diazotroph community structure in Lyngbya sp. and Microcoleus chthonoplastes dominated microbial mats from Guerrero Negro, Baja, Mexico. FEMS Microbiology Ecology 47: 305-318.

Omoregie, E. O., L. L. Crumbliss, B. M. Bebout, and J. P. Zehr. 2004. Determination of nitrogen-fixing phylotypes in Lyngbya sp. and Microcoleus chthonoplastes cyanobacterial mats from Guerrero Negro, Baja, Mexico. Applied and Environmental Microbiology 70: 2119-2128.

Visscher, P. T., S. E. Hoeft, T. L. Surgeon, D. R. Rogers, B. M. Bebout, J. S. Thompson, Jr., and R. P. Reid. 2002. Microelectrode measurements in stromatolites: Unraveling the Earth's past?, p. 265-282. In M. Taillefert and T. F. Rozan [eds.], Environmental Electrochemistry: Analysis of Trace Element Biogeochemistry. American Chemical Society.

Bebout, B. M., S. P. Carpenter, D. J. Des Marais, M. Discipulo, T. Embaye, F. Garcia-Pichel, T. M. Hoehler, M. Hogan, L. L. Jahnke, R. M. Keller, S. R. Miller, L. E. Prufert-Bebout, C. Raleigh, M. Rothrock, and K. Turk. 2002. Long term manipulations of intact microbial mat communities in a greenhouse collaboratory: Simulating Earth's present and past field environments. Astrobiology 2: 383-402.

Hoehler, T. M., D. B. Albert, M. J. Alperin, B. M. Bebout, C. S. Martens, and D. J. Des Marais. 2002. Comparative ecology of H2 cycling in sedimentary and phototrophic ecosystems. Antonie van Leeuwenhoek 81: 575-585.

Hoehler, T. M., B. M. Bebout, and D. J. Des Marais. 2001. The role of microbial mats in the production of reduced gases on the early Earth. Nature 412: 324-327.
Visscher, P. T., R. P. Reid, and B. M. Bebout. 2000. Microscale observations of sulfate reduction: Correlation of microbial activity with lithified micritic laminae in modern marine stromatolites. Geology 28: 912-922.

Reid, R. P., P. T. Visscher, A. W. Decho, J. F. Stolz, B. M. Bebout, C. Dupraz, I. G. Macintyre, H. W. Paerl, J. Pinckney, L. Prufert-Bebout, T. F. Steppe, and D. J. Des Marais. 2000. The role of microbes in accretion, lamination and lithification in modern marine stromatolites. Nature 406: 989-992.

Visscher, P. T., R. P. Reid, B. M. Bebout, S. E. Hoeft, I. G. Macintyre, and J. A. Thompson, Jr. 1998. Formation of lithified micritic laminae in modern marine stromatolites (Bahamas): The role of sulfur cycling. American Mineralogist 83: 1482-1493.

Ferdelman, T. G., C. Lee, S. Pantoja, J. Harder, B. M. Bebout, and H. Fossing. 1997. Sulfate reduction and methanogenesis in a Thioploca-dominated sediment off the coast of Chile. Geochimica et Cosmochimica Acta 61: 3065-3079.

Garcia-Pichel, F., and B. M. Bebout. 1996. Penetration of ultraviolet radiation into shallow water sediments: High exposure for photosynthetic communities. Marine Ecology Progress Series 131: 257-262.

Paerl, H. W., M. Fitzpatrick, and B. M. Bebout. 1996. Seasonal nitrogen fixation dynamics in a marine microbial mat: Potential roles of cyanobacteria and microheterotrophs. Limnology and Oceanography 41: 419-427.

Pinckney, J., H. W. Paerl, and B. M. Bebout. 1995. Salinity control of benthic microbial mat community production in a Bahamian hypersaline lagoon. Journal of Experimental Marine Biology and Ecology 187: 223-237.

Bebout, B. M., and F. Garcia-Pichel. 1995. UVB-induced vertical migrations of cyanobacteria in a microbial mat. Applied and Environmental Microbiology 61: 4215-4222.

Pinckney, J., H. W. Paerl, R. P. Reid, and B. Bebout. 1995. Ecophysiology of stromatolitic microbial mats, Stocking Island, Exuma Cays, Bahamas. Microbial Ecology 29: 19-37.

Kohlmeyer, J., B. Bebout, and B. Volkmann-Kohlmeyer. 1995. Decomposition of mangrove wood by marine fungi and teredinids in Belize. P.S.Z.N.I. Marine Ecology 16: 27-39.

Bebout, B. M., H. W. Paerl, J. E. Bauer, D. E. Canfield, and D. J. Des Marais. 1994. Nitrogen cycling in microbial mat communities: The quantitative importance of N-fixation and other sources of N for primary productivity, p. 265-271. In L. J. Stal and P. Caumette [eds.], Microbial Mats: Structure, Development and Environmental Significance. NATO ASI Series. Springer-Verlag.

Stal, L. J., H. W. Paerl, B. M. Bebout, and M. Villbrandt. 1994. Heterocystous versus non-heterocystous cyanobacteria in microbial mats, p. 403-414. In L. J. Stal and P. Caumette [eds.], Microbial Mats: Structure, Development and Environmental Significance. NATO ASI Series. Springer-Verlag.

Paerl, H. W., B. M. Bebout, C. A. Currin, M. W. Fitzpatrick, and J. L. Pinckney. 1994. Nitrogen fixation dynamics in microbial mats, p. 325-337. In L. J. Stal and P. Caumette [eds.], Microbial Mats: Structure, Development and Environmental Significance. NATO ASI Series. Springer-Verlag.

Paerl, H. W., B. M. Bebout, S. B. Joye, and D. J. Des Marais. 1993. Microscale characterization of dissolved organic matter production and uptake in marine microbial mat communities. Limnology and Oceanography 38: 1150-1161.

Bebout, B. M., M. W. Fitzpatrick, and H. W. Paerl. 1993. Identification of the sources of energy for nitrogen fixation and physiological characterization of the nitrogen-fixing members of a marine microbial mat community. Applied and Environmental Microbiology 59: 1495-1503.

Paerl, H. W., and B. M. Bebout. 1992. Oxygen dynamics in Trichodesmium spp. aggregates, p. 43-60. In E. J. Carpenter, D. G. Capone and J. G. Rueter [eds.], Marine Pelagic Cyanobacteria: Trichodesmum and other Diazotrophs. Kluwer Academic Press.

Paull, C. K., A. C. Neumann, B. Bebout, V. Zabielski, and W. Showers. 1992. Growth rate and stable isotopic character of modern stromatolites from San Salvador, Bahamas. Palaeogeogr. Palaeoclimatol. Palaeoecol. 95: 335-344.

Carpenter, E. J., J. Chang, M. Cottrell, J. Schubauer, H. W. Paerl, B. M. Bebout, and D. G. Capone. 1990. Re-evaluation of nitrogenase oxygen-protective mechanisms in the planktonic marine cyanobacterium Trichodesmium. Marine Ecology Progress Series 65: 151-158.

Paerl, H. W., B. M. Bebout, and L. E. Prufert. 1989. Bacterial associations with marine Oscillatoria sp. (Trichodesmium sp.) populations: Ecophysiological implications. Journal of Phycology 25: 773-784.

Paerl, H. W., B. M. Bebout, and L. E. Prufert. 1989. Naturally occurring patterns of oxygenic photosynthesis and N2 fixation in a marine microbial mat: Physiological and ecological ramifications, p. 326-341. In Y. Cohen and E. Rosenberg [eds.], Microbial Mats: Physiological Ecology of Benthic Microbial Communities. American Society for Microbiology.

Paerl, H. W., B. M. Bebout, and L. E. Prufert. 1988. Physiological ecology and environmental control of N2 fixation in marine and freshwater microbial associations, p. 711-716. In H. Bothe, F. J. de Bruijn and W. E. Newton [eds.], Nitrogen Fixation: Hundred Years After. Gustav Fischer, Stuttgart.

Paerl, H. W., and B. M. Bebout. 1988. Direct measurement of O2-depleted microzones in marine Oscillatoria: Relation to N2 fixation. Science 241: 442-445.

Bebout, B. M., H. W. Paerl, K. M. Crocker, and L. E. Prufert. 1987. Diel interactions of oxygenic photosynthesis and N2 fixation (acetylene reduction) in a marine microbial mat community. Applied and Environmental Microbiology 53: 2353-2362.

Bebout, B., J. Kohlmeyer, S. Schatz, and M. Haibach. 1987. Temperature-dependent growth in isolates of Corollospora maritima Werderm. (Ascomycetes) from different geographical regions. Journal of Experimental Marine Biology and Ecology 106: 203-210.

Kohlmeyer, J., and B. Bebout. 1986. On the occurrence of marine fungi in the diet of Littorina anguilifera and observations on the behavior of the periwinkle. P.S.Z.N.I. Marine Ecology 7: 333-343.
Curriculum Vita: 
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