Our laboratory studies the physiology and ecology of hyperthermophilic archaea and the geomicrobiology of hydrothermal environments. Our main study sites are the hydrothermal vent systems at Axial Volcano and the Endeavour Segment, both part of the Juan de Fuca Ridge off the west coast of the USA. Below are descriptions of our current projects and some relevant publications.

Geomicrobiology of deep-sea hydrothermal vents

This project examines the spatial distribution, metabolic processes, and growth constraints of hyperthermophilic archaea in deep-sea hydrothermal vent environments. We are also working with others to determine the overall diversity, distribution, and impact of microorganisms on hydrothermal fluids and black smoker chimneys and their relationship with the mineralogy and fluid chemistry of this environment. Our primary study sites have been along the Juan de Fuca Ridge, namely the Endeavour Segment, and Axial Volcano, in the northeastern Pacific Ocean where the Holden lab has been collecting samples since 2004.

Ver Eecke, H.C., D.A. Butterfield, J.A. Huber, M.D. Lilley, E.J. Olson, K.K. Roe, L.J. Evans, A.Y. Merkel, H.V. Cantin, and J.F. Holden (2012) Hydrogen-limited growth of hyperthermophilic methanogens at deep-sea hydrothermal vents. Proc. Natl. Acad. Sci. USA 109:13,674-13,679. [PDF] [supplement]

Holden, J.F., J.A. Breier, K.L. Rogers, M.D. Schulte, and B.M. Toner (2012) Biogeochemical processes at hydrothermal vents: microbes and minerals, bioenergetics, and carbon fluxes. Oceanography 25:196-208

Ver Eecke, H.C., D.S. Kelley, and J.F. Holden (2009) Abundances of hyperthermophilic autotrophic Fe(III) oxide reducers and heterotrophs in deep-sea hydrothermal sulfide chimneys of the northeastern Pacific Ocean. Appl. Environ. Microbiol. 75:242-245. [PDF] [supplement]

Dissimilatory iron reduction in hyperthermophilic archaea

This project examines dissimilatory iron reduction in hyperthermophilic Crenarchaeota, namely in Hyperthermus, Pyrodictium, and Pyrobaculum species. Our ongoing work with Hyperthermus and Pyrodictium species models the rates and constraints of growth and examines biogenic mineral transformations catalyzed by these organisms. Previous work with Pyrobaculum examined shifts in protein composition with change in terminal electron acceptor.

Holden, J.F., A.L. Menon, and M.W.W. Adams (2011) Hyperthermophile-metal interactions in hydrothermal environments, pp. 39-63. In J.F. Stolz and R.S. Oremland (eds.), Microbial Metal and Metalloid Metabolism: Advances and Applications, ASM Press, Washington, DC.

Feinberg, L.F., R. Srikanth, R.W. Vachet, and J.F. Holden (2008) Constraints on anaerobic growth in the hyperthermophilic archaea Pyrobaculum islandicum and Pyrobaculum aerophilum. Appl. Environ. Microbiol. 74:396-402. [PDF] [supplement]

Feinberg, L.F., and J.F. Holden (2006) Characterization of dissimilatory Fe(III) versus NO3- reduction in the hyperthermophilic archaeon Pyrobaculum aerophilum. J. Bacteriol. 188:525-531. [PDF] [erratum]

Modeling subsurface chemolithoautotrophic microbial ecosystems

This project models the bioenergetics of aphotic, anaerobic primary production within rocky portions of the Earth's crust. The goal is to measure rates of energy expenditure for various groups of anaerobes and then compare these with energy fluxes to that environment to predict habitability and biogeochemical impact on that environment.

Waste-to-hydrogen conversion by hyperthermophilic heterotrophs

This project examines the ability of hyperthermophilic heterotrophs, such as Pyrococcus and Thermococcus species, to convert sugars and peptides into hydrogen and other secondary metabolites. The long-term goal is to determine the feasibility of using these organisms to convert sewage and agricultural waste into bioenergy products and other industrially useful precursors.

Girguis, P.R., and J.F. Holden (2012) On the potential for bioenergy and biofuels from hydrothermal vent microbes. Oceanography 25:213-217

Oslowski, D.M., J.H. Jung, D.H. Seo, C.S. Park, and J.F. Holden (2011) Production of hydrogen from {alpha}-1,4- and {beta}-1,4-linked saccharides by marine hyperthermophilic archaea. Appl. Environ. Microbiol. 77:3169-3173. [PDF] [supplement - Word document]