Deb Aronson

Bruce Fouke

The Intersection of Geology & Microbes

First appeared in Biomarker in December 2009 under Profiles

Bruce Fouke, a sedimentary geologist, started his academic research journey in a fairly conventional way; integrating sedimentology, stratigraphy, geochemistry and paleontology to reconstruct the Earth’s environment during the deposition and secondary alteration of sedimentary rocks.

But since beginning his research at Illinois Fouke has traveled a long and winding road that connects the coral reefs of the Netherlands Antilles, the hot springs in Yellowstone National Park and Tuscany, meteor ejecta in the Yucatan, Roman aqueducts, aquifers and oil fields in rural Illinois, and, ultimately, microbes.

Microbes? Why would a geologist be interested in microorganisms? The answer, while not simple, underscores the collegiality and interdisciplinary nature of the University of Illinois and the IGB.

It turns out that Fouke, associate professor of geology and one of the founders, along with Carl Woese and Nigel Goldenfeld, of the Biocomplexity theme at IGB, recognized the importance of microbes to his research shortly after arriving at the University of Illinois in 1997. That is when he learned that microbes control the major chemical cycles of the world’s oceans. Since he was investigating sedimentation as a way to understand ancient marine environments, he decided he had to understand microbiology.

“How can we do geology without understanding microbes?” asks Fouke, somewhat rhetorically.

Fouke apprenticed himself to Abigail Salyers, professor of microbiology and a member of IGB’s Host-Microbe Systems theme, who helped him learn techniques, like PCR, for sequencing genes in order to identify which microbes are present and what they are doing metabolically to sustain themselves.

After setting up his own lab, complete with a PCR machine, thermocycler, other equipment and a postdoctorate researcher with a Ph.D. in microbiology, Fouke began looking at microbes in all the places he already was working. Fouke’s efforts were consistently buoyed by ongoing close collaborations with the Department of Microbiology, as well as microbiologists and scientists interested in microbiology from across the Illinois campus. And his ability to work with microbes opened up a new window into his understanding of sedimentation.

Fouke is on the leading edge of a whole new way of asking and answering geological questions. “I’m one of a small group of people who come at this from the geological side to engage the molecular microbiology, but the field is now rapidly growing,” says Fouke of this marriage of microbiology and geology, or geobiology.

Microbial activity can play a key role in modifying water chemistry, thus changing the conditions available for precipitation of minerals such as carbonates. At the same time, precipitates themselves modify the water flow pattern and the transport of microbes, creating a dynamic interplay between the biological activity and the spatial geological structures that emerge at hot springs. It is possible, then, that changes in, for example, calcium carbonate sedimentation rates in the geological record at the hot springs of Yellowstone National Park may have resulted from changes in local microbial biomass concentrations throughout geologic history.

“As calcium carbonate minerals are precipitated, it leaves a chemical fingerprint of the animals and environment, the plants and bacteria that were there,” said Fouke.

By identifying and then understanding these kinds of microbe-water-mineral interactions, Fouke hopes to be able to distinguish between deposits that are directly precipitated by microorganisms, indirectly precipitated by them or inorganically precipitated. Only when he can distinguish between these deposits will he be able to determine how the organism-environment feedback controls geological preservation and the creation of a fossil record.

At this same intersection of microorganisms and geology Fouke also is applying his research to the production and extraction of oil and gas. As a co-principal investigator in the Microbially Enhanced Hydrocarbon Recovery (MEHR) project sponsored by the Energy Biosciences Institute (EBI), a part of IGB funded by BP, Fouke is studying the naturally occurring microorganisms that exist in the subsurface and are associated with the subsurface migration and entrapment of hydrocarbons.

This project is taking place in Decatur and is co-sponsored by the Midwest Geological Carbon Sequestration Consortium and the Illinois State Geological Survey (ISGS). Fouke has collaborated with members of ISGS for many years and holds an appointment in their division. Archer Daniels Midland is providing the wells for the study.

Fouke and other EBI researchers will study the genetic makeup of microbial communities found in the water and rock samples extracted from the wells. Microbes are thought to interact with oil and other resources, causing them to become more viscous or liquid. If this is the case, and the microbes can be identified and cultured, Fouke hopes the team will be able to use the microbes, or even enhance their ability to break down oil and make it possible to extract more of it.

“If we can get even another five percent out of existing oil wells, that represents an enormous amount of oil,” says Fouke.

Even more importantly, this project gives researchers an opportunity to study the Earth’s subsurface, which is a vast and mostly unknown ecosystem that is “just as important as any national park,” says Fouke, who sees himself as a steward of the subsurface. “This project could be a major step forward for subsurface ecosystem sustainability and management.”