Eric Boyd, Post doctoral fellow
Montana State University
Department of Chemistry and Biochemistry
224 Chemistry and Biochemistry & Building
Bozeman, MT 59717
Microorganisms are inextricably linked to the environments that they inhabit; a relationship that undoubtedly results in adaptation at the genomic and physiological levels. My research utilizes contemporary and systems microbiological approaches to better understand the genetics and physiology of biological sulfur and hydrogen cycling.
Sulfur Cycling. Many acid geothermal springs in Yellowstone National Park (YNP) contain copious amounts of elemental sulfur (S°) suggesting the presence of organisms capable of utilizing this inorganic compound for respiration. The origin of solid-phase S° near the point of discharge in acidic geothermal springs can be attributed to biotic oxidation of H2S as well as abiotic H2S oxidation to thiosulfate (S2O32-), which disproportionates under acidic conditions to form sulfite (SO3-) and S°. Despite the abundance of S°, little remains known concerning the identity, physiology, or ecology of organisms that depend upon this abundant electron donor/acceptor in geothermal environments in Yellowstone National Park, Wyoming.
We have successfully isolated two novel sulfur-respiring, thermoacidiphilic Crenarchaea that couple the oxidation of peptides to the obligate reduction of S°. Quantitative polymerase chain reaction (qPCR) indicates that both organisms represent a significant fraction (12-37% of total DNA) of the microbial community present in a variety of sulfide-rich and acidic environments. Currently, my research aims at better understanding the mechanisms by which Crenarchaea reduce elemental sulfur under acidic conditions and the acclimation of Crenarchaea to growth in acid. These questions are being approached using a combination of geochemical, molecular, and analytical methodologies including voltametry, genoxmics, and lipid analysis.
Hydrogen Cycling. Hydrogenase enzymes are Fe-S proteins that catalyze the reversible oxidation of molecular hydrogen and are likely to be amongst the earliest of catalytic biomolecules. Hydrogenases are widely distributed amongst the archaea, bacteria, and eukarya and belong to one of two structurally-distinct classes: the [FeFe]- or [NiFe]-hydrogenases. Both classes of enzyme exhibit similar active site architecture which contains unique cyanide and carbon monoxide ligands (Fig. 1A and 1B) as well as Fe-S clusters. Together, these structural similarities, are thought to confer common catalytic activity. Despite similarities between the [FeFe]- and [NiFe]-hydrogenases, they are phylogenetically unrelated. Recent genomic sequencing efforts have revealed interesting distributional patterns for each class of enzyme. For example, the [FeFe]-hydrogenase is widely distributed amongst the bacteria and the eukarya but does not occur in the archaea. Another perplexing observation is the occurrence of the [NiFe]-hydrogenase in the bacteria and archaea but not in the eukarya. Collectively, these observations suggest an independent evolutionary origin for each class of enzyme and an evolutionary convergence to catalyze similar chemistry; however, the basis for this convergence is unclear.
Using a suite of molecular, geochemical, and phylogenetic methods, we seek to better define the evolutionary origin and history of [FeFe]- and [NiFe]-hydrogenases and to investigate the relationship between gene distribution among taxa and aqueous- and solid-phase geochemistry. Similarly, we will use the genetic record of hydrogenase genes to investigate the environmental and/or phylogenetic basis for the evolution of similar catalytic properties in two phylogenetically-unrelated proteins.
B.Sc., Iowa State University, Advisor: Dr. Alan DiSpirito
Ph.D., Montana State University, Advisor: Dr. Gill Geesey
Grants, Awards, and Affiliations
Scholarship Chairman, Beta Theta Pi Fraternity
Beta Beta Beta Biological Honor Society
American Society for Microbiology
Inland Northwest Research Alliance Fellowship
Montana State University Fergusson Graduate Fellowship
Montana University System Water Center Fellowship
NASA Astrobiology Institute Fellowship
Gill Geesey, Montana State University
Ann Pearson, Harvard University
Chuanlun Zhang, University of Georgia
Mark Skidmore, Montana State University
Jeff Boyd, University of Wisconsin
Hans-Peter Klenk, DSMZ Culture Collection, Germany
Tamar Barkay, Rutgers University
D. Kirk Nordstrom, United States Geological Survey
Jeffery K. Tomberlin, Texas A&M University
David C. Cummings, Point Loma Nazarene University
Alan A. DiSpirito, Iowa State University
James A. Zahn, Coskata Energy, Illinois
Gregory K. Druschel, University of Vermont
Melissa Lafreniere, Queens University, Canada
Beer, LL; Boyd, ES; Peters, JW; Posewitz, MC. Engineering algae for biohydroen and biofuel production. Curr. Opin. Biotechnol. 2009. 20: 264-271.
Boyd, ES; Spear, JR; Peters, JW. [FeFe] hydrogenase genetic diversity provides insight into molecular adaption in a saline microbial mat community. Appl. Environ. Microbiol. 2009; 75: 4620-4623.
Boyd, ES; Leavitt, WD; Geesey, GG. CO(2) uptake and fixation by a thermoacidophillic microbial community attached to precipitated sulfur in a geothermal spring. Appl. Environ. Microbiol. 2009; 75: 4289-4296
Boyd ES; King S; Tomberlin JK; Nordstrom DK; Krabbenhoft DP; Barkay T; Geesey GG. Methylmercury enters an aquatic food web through acidophilic microbial mats in Yellowstone National Park, Wyoming. Enviorn Microbiol. 2009; 11: 950-959.
Krishnakumar, AM; Sliwa, D; Endrizzi, JA; Boyd, ES; Ensign, SA; Peters, JW. Getting a handle on the role of coenzyme M in alkene metabolism. Microbiol. Mol. Biol. Rev.; 72: 445-456.
Boyd, E.S., A. Pearson, Y. Pi, W.-J. Li, C.L. Zhang, G.G. Geesey. 2007. Physicochemical influences on glycerol dialkyl glycerol tetraether lipid composition in the crenarchaeote Acidilobus sulfurireducens. Appl. Environ. Microbiol. In review.
Boyd, E.S., R.A. Jackson, G. Encarnacion, J.A. Zahn, T. Beard, W.D. Leavitt, Y. Pi, C.L. Zhang, A. Pearson, and G.G. Geesey. 2007. Isolation, characterization, and ecology of sulfur-respiring Crenarchaeota inhabiting acid-sulfate-chloride geothermal springs in Yellowstone National Park. Appl. Environ. Microbiol. 73 (20): 6669-6677.
Boyd, E.S., D.C. Cummings, and G.G. Geesey. 2007. Mineralogy influences structure and diversity of bacterial communities associated with geological substrata in a pristine aquifer. Microb. Ecol. 54 (1): 170-182.
Choi, D.W, Y.S. Do, C.J. Zea, M.T. McEllistrem, S-W. Lee, J.D. Semrau, N.L. Pohl, C.J. Kisting, E.S. Boyd, G.G. Gessey, T.P. Riedel, P.H. Shafe, K.A. Kranski, J.R. Tritsch, W.E. Antholine, and A.A. DiSpirito. 2006. Spectral and thermodynamic properties of Ag(I), Au(III), Cd(II), Co(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(IV), and Zn(II) binding by Methanobactin from Methylosinus trichosporium OB3b. J. Inorg. Biochem. 100 (12): 2150-2161.
Choi, D.-W., C.J. Zea, Y.S. Do, J.D. Semrau, W.E. Antholine, C.J. Kisting, M.S. Hargrove, N.L. Pohl, E.S. Boyd, G.G. Geesey, D. Campbell, V. Rao, S.C. Hartsel, M.T. McEllistrem, A.M. de la Mora, and A.A. DiSpirito. 2005. Spectral, kinetic, andthermodynamic properties of Cu(I)- and Cu(II)-binding by methanobactin from Methylosinus trichosporium OB3b. Biochem. 45 (5): 1442- 1453.
Choi, D.-W., R.C. Kunz, E.S. Boyd, J.D. Semrau, W.E. Antholine, J.-I. Han, J.A. Zahn, J.M. Boyd, A.M. de la Mora, A.A. DiSpirito. 2003. Isolation of the membrane- associated methane monooxygenase and the NADH:quinone oxidoreductase- membrane-associated methane monooxygenase complex from Methylococcus capsulatus Bath. J. Bacteriol. 185 (19): 5755-5764.
Do, Y.S., T.M. Schmidt, J.A. Zahn, E.S. Boyd, and A.A. DiSpirito. 2003. Role of Rhodobacter sp. PS9, a purple non-sulfur photosynthetic bacterium isolated from an anaerobic swine waste lagoon involved in odor remediation. Appl. Environ. Microbiol. 69 (3): 1710-1720.