Novel approaches to microbial geochemistry and
Christopher H. House, Ph.D.
Penn State University
Monday, October 1, 2001
12:00 Noon–Pacific Forum
The goal of the field of microbial geobiology is to determine the
evolutionary history of microorganisms and to understand the impact that
these microbes have had in shaping the environment. This work requires the
integration of microbial paleontology, geochemistry, and phylogenetics.
My recent work on microbial paleontology used SIMS (Secondary Ion Mass
Spectrometry) to determine the carbon isotopic composition of microbial
fossils from several Precambrian fossil localities (up to 2 billion years)
in order to constrain their carbon fixation biochemistry. The results were
consistent with these microbes having used the Calvin Cycle.
Using the technique (in collaboration with MBARI), the carbon isotopic
composition of archaeal-bacterial consortia were determined indicating
growth on methane.
Because phylogenetic trees (rRNA trees) are a principle method for
studying the evolutionary history of organisms, I am also interested in
testing the rRNA tree and developing new ways to create universal trees.
Next: Ecophysiology of gelatinous organisms in hypoxia