The School of Molecular and Cellular Biology at the University of Illinois at Urbana-Champaign

Can microbe-water-mineral interactions be tracked in modern environments and used to reconstruct ancient microbial activity from carbonate rocks on Earth and other planets? What microbial communities inhabit the surface of healthy and diseased coral tissues and how do they vary in response to changing global marine environmental conditions?

My ongoing geomicrobiology research is to determine how the activity of specific living microbes or microbial communities influence the precipitation of common carbonate mineral deposits. Results are providing a fundamental knowledge of microbe-water-mineral interactions during carbonate precipitation that are required to more accurately reconstruct the history of microbial life on earth and other planets. This work combines geological studies, microbial rDNA and gene analyses and quantitative system-scale modeling to provide a detailed account of biotic versus abiotic carbonate mineral precipitation. Two studies are in progress, which include analyses of: (1) the control exerted by thermo- and mesophilic bacteria on the shape and chemistry of carbonate minerals precipitated in hot springs of Yellowstone National Park; and (2) the ecology and source of bacteria responsible for causing coral disease in Caribbean and Indo-Pacific coral reef ecosystems.

Hot Spring Biomineralization: Five distinct environments of hot spring carbonate mineral deposits, called travertine, have been observed along spring outflow channels at Mammoth Hot Springs based on water chemistry and travertine crystal form and chemistry. The aqueous chemistry of the hot spring drainage system is dominated by CO2 degassing and dropping temperature. While these physical factors help drive the rapid precipitation of carbonate crystals to deposit travertine at rates as high as 5 mm/day, significant bacterial controls on travertine crystal form and isotope chemistry have been identified (e.g. crystals entombing and preserving the shape of filamentous Aquificales bacteria). Travertine isotope compositions indicate bacterial influence during travertine deposition that increases in magnitude from the high (73°C) to the low (<25°C) temperature portions of the spring outflow. Bacterial 16S rRNA screening has revealed 657 unique bacterial rDNA types representing 21 divisions, which exhibit a remarkable 85% partitioning along the spring outflow. Change in the chemical saturation state of the spring water coincides with metabolic transitions from predominantly autotrophic to heterotrophic bacterial communities. Comparative analyses are now being conducted on hot springs near Siena, Italy.

The main question being addressed is whether the presence of terraced carbonate mineral deposits is prima facie evidence for the presence of microbial activity. Current research includes: 1) performing in situ crystallization experiments to determine the form and chemistry of travertine deposited when the microbes have been UV-irradiated, a sterilization technique that will leave the other fundamental physical and chemical conditions of the spring drainage outflow relatively unchanged; 2) documenting associations between calcite crystal growth form, distribution and chemistry with microbial form, diversity and metabolic activity; and 3) quantitative modeling of carbonate terrace formation using stochastic differential equations to describe the combined effects of geological and biological processes.

Coral Disease: Systematic changes have been observed in the composition and diversity of bacterial communities inhabiting the surface and overlying seawater of three coral species infected with black band disease (BBD) on the southern Caribbean island of Curaçao, Netherlands Antilles. PCR amplification and sequencing of bacterial 16S rRNA genes with universally conserved rDNA primers has identified over 524 unique bacterial sequences affiliated with 12 bacterial divisions. The molecular sequences exhibited less than 5% similarity in bacterial community composition between seawater and the healthy, black band diseased, and dead coral surfaces. Clone libraries from the BBD bacterial mat, which rapidly migrates across and kills the coral tissue, were comprised of eight bacterial divisions and 13% unknowns. Several sequences representing bacteria previously found in other marine and terrestrial organisms (including humans) were isolated from the infected coral surfaces, including Clostridium sp., Arcobacter sp., Campylobacter sp., Cytophaga fermentans, C. columnaris, and Trichodesmium tenue. The presence of these and other affiliated sequences in the coral surface clone libraries may imply that human sewage, infection from other marine organisms, and terrestrial runoff may have combined to influence the development of BBD in corals on the Curaçao reef tract. In situ transplantation and inoculation experiments, as well as work on other coral diseases such as "pink blotch" are now being conducted on coral reefs of the Netherlands Antilles and Papua New Guinea.

Representative Publications

Yellowstone Hot Spring Geomicrobiology

Fouke, B.W., 2011. Hot-Spring Systems Geobiology: Abiotic and Biotic Influences on Travertine Formation at Mammoth Hot Springs, Yellowstone National Park, USA. Sedimentology, 58:170-219.

Inskeep, W.P., Rusch, D.B., Jay, Z., Herrgard, M.J., Kozubal, M.A., Richardson, T.B., macur, R.E., Hamamura, N., Jennings, R., Fouke, B.W., Reysenbach, A.L., Roberto, F., Young, M., Bateson, M., Schwartz, A., Boyd, E., Badger, J., Geesey, G., Mathur, E., Frazier, M., 2010, Metagenomes from high-temperature chemotrophic systems reveal importance of geochemical controls on microbial community structure and function. PLoS One 5(3):1-15.

Kandianis, M., Fouke, B.W., Johnson, R., Veysey, J., Inskeep, W., 2008. Microbial biomass: a catalyst of CaCO3 precipitation in advectively dominated regimes. GSA Bulletin, Vol. 119 (12) in press. DOI: 10.1130/B26188.1

Zhang, C.L., Fouke, B.W., Bonheyo, G.T., White, D., Huang, Y., and Romanek, C.S., 2004, Lipid biomarkers and carbon isotopes of modern travertine deposits (Yellowstone National Park, USA): Implications for biogeochemical dynamics in hot-spring systems: Geochimica et Cosmochimica Acta. Vol. 68, p. 3157-3169.

Coral Reef Geomicrobiology

Klaus, J.S., Janse, I., and Fouke, B.W., 2011. Coral black band diseae microbial communities and genotypic variability of the dominant cyanobacteria (CD1C11). Bulletin of Marine Science 87:795-821.

Piggot, A.M., Fouke, B.W., Sivaguru, M., Sanford, R., Gaskins, H.R., 2009. Change in zooxanthellae and mucocyte tissue density as an adaptive response to environmental stress by the coral Montastraea annularis, Marine Biology 156:2379-2389.

Klaus, J., Janse, I., Sandford, R., and Fouke, B.W., 2007. Coral microbial communities, zooxanthellae, and mucus along gradients of seawater depth and coastal pollution. Environmental Microbiology, Vol. 9(5):1291-1305.

Klaus, J.S., Frias-Lopez, J., Bonheyo, G.T., Heikoop, J.M., and Fouke, B.W. 2005. Bacterial communities inhabiting the healthy tissues of two Caribbean reef corals: interspecific and spatial variation. Coral Reefs, 24:129–37.

Complete Publications List