Novel approaches to microbial geochemistry and microbial phylogenetics

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