Office: BSF 132
Lab: BSF 122, BSF 124
Ph.D. Biology, Penn State at University Park, 1998.
Post Doctoral Fellow, Harvard University.
Microbial physiology and biogeochemistry
Autotrophic microorganisms from all three domains of life (Bacteria, Archaea, and
Eukarya) proliferate under a dizzying array of conditions. These organisms fix carbon
dioxide while growing in more familiar habitats like lakes and oceans, but also
thrive in extreme environments such as terrestrial hot springs, deep-sea hydrothermal
vents and hydrocarbon seeps, acid rock drainage, and the subsurface biosphere.
Added to this breadth in habitats is a breadth in history. The three domains of
life are believed to have originated rather early in Earth history, by 2.7 billion
years ago. Since that time, the atmospheric concentration of carbon dioxide has
fallen by nearly three orders of magnitude, while atmospheric oxygen, which inhibits
some carbon fixing enzymes, has risen from nil to its current level of 21% by volume.
My major research question is, how have these organisms adapted to these changes?
How do they fix carbon despite low concentrations of carbon dioxide, and elevated
concentrations of oxygen? Have organisms within Bacteria and Archaea devised many
different mechanisms for coping with these conditions, or did a few efficient methods
(e.g., carbon concentrating mechanisms, carbonic anhydrases) originate fairly early
on and are currently used by phylogenetically broad groups of organisms?
Given that many key autotrophic organisms are uncultivable, it is necessary for
me to use a rather broad arsenal of methods to study them, including molecular tools
and mass spectrometry. Elucidating the answers to the questions I raise above promises
to have a substantial effect on our understanding of geochemical cycles and autotroph
physiology, as well as their response to anthropogenic increases in atmospheric
Microbial Physiology and Biogeochemistry