The Microbial Ecology Program at the University of Montana currently has 5 available RA’s for the Fall 2004 academic year. Most of the projects are multi-year. The average stipend is $18,000 (+ tuition and partial fees). A brief lay abstract for each project can be found below. For Further information contact jim.gannon@umontana.edu

Nyack Microbial Observatory General Abstract

(Project Research Directors: J. Gannon 1, W. Holben 1, W. Woessner 2, B. Ellis 3 and J. Stanford 3)

University of Montana: 1Microbial Ecology Program, 2Geology Program, 3Flathead Lake Biological Station

Beginning in the Bob Marshall Wilderness of Montana and the southern part of Glacier National Park, the Middle Fork of the Flathead River flows through narrow canyons until it reaches the glacier-carved Nyack Flood Plain. The floodplain is home to numerous wildlife species, including threatened grizzly bear, gray wolf, and bull trout. As the river enters the upstream end of the valley, 30 percent of the flow enters a shallow aquifer (hyporheic) before eventually re-entering to the river channel down stream. An abundance of large-bodied insects with life cycle stages uniquely tied to the hyporheic habitat have been discovered here. This terrestrial to aquatic interface can be visualized as a pristine food web where nutrients washed from the forest floor are “re-packaged” into microorganisms and then transferred to aquatic insects, who, in turn, are consumed by fish, and so on up the food chain. Hyporheic habitats, found throughout the world, are critical to nutrient cycles that maintain and rejuvenate all of life in the river corridor. Despite their importance, the microorganisms of the hyporheos are largely unknown. Understanding who they are and what controls their diversity and abundance is the overarching goal of the Nyack Microbial Observatory .

Photo of the Nyack Flood plain from GNP (photo by J.A. Stanford, FLBS)

The project site is the Nyack Floodplain Research Natural Area, operated by the Flathead Lake Biological Station (http://www.umt.edu/biology/flbs/home.htm) in cooperation with the John Dalimata Family, the National Park Service and the US Forest Service.  A separate NSF project (http://www.umt.edu/biology/flbs/Research/Biocomplexity.htm) has mapped the flood plain hyporheic boundary in 3 dimensions and has installed approximately 100 sampling wells. Using this infrastructure, the Nyack Microbial Observatory will explore the hyporheic community with the intent to quantify, cultivate, and characterize novel microorganisms and measure factors that shape the microbial community and link microbial diversity to higher organisms. We seek a broader understanding of floodplain/river health as mediated by flux of water and materials through the river and its floodplain aquifer. The 5 year project, beginning in summer of 2004 will use a suite of innovative molecular, microbiological, and hydrological tools to monitor microbial communities across seasons and along this unique hyporheic gradient.

Centaurea invasions: From molecules and microbes to plant communities

 (Project PI, William Holben and Ray Callaway)

 Our research is designed to investigate mechanisms by which some plant species that are relatively rare in their native environments can become dominants where they are introduced. We intend to do this by studying the effects of chemicals exuded from the roots of Centaurea maculosa, one of the western USA’s worst invaders, on native microbial communities and native plant communities. Furthermore, we will conduct comparative experiments using European and North American soil communities and plant species. We have organized our research around the following hypotheses: 1) Centaurea affects soil microbial communities and plant communities through root exudates, 2) negative effects on microbial and plant taxa are mediated, at least in part, by the microbiocidal compound (±) catechin. 3) Some taxa in microbial communities in soils from the native range of Centaurea (e.g. French soils) have adapted to the suppressive effects of (±) catechin. This research has the potential to develop new theory on invasive weeds and in doing so also contribute to general ecological theory. Conversely, developing this theory should contribute a great deal to understanding invasion and the development of methods to control weeds.

Temperature adaptation of autotrophic carbon metabolism in ecologically diverse hot spring Synechococcus: An integrative study of extreme photosynthesis

 (Project PI, Scott Miller)

Identifying the changes in genomes responsible for changes in ecology is a fundamental challenge for all of biology, but a particularly urgent one for the study of microorganisms since they are the most genetically and ecologically diverse organisms on the planet. In this project we will integrate across all levels of biological organization, from the molecular to the ecological, in our investigation of the temperature adaptation of photosynthetic carbon metabolism in related hot spring cyanobacteria of the genus Synechococcus with divergent thermal ecologies. It builds on molecular evolutionary evidence for the temperature adaptation of photosynthesis genes by testing the functional and ecological consequences of these genetic changes. By assaying photosynthesis at different temperatures in ecologically diverse Synechococcus strains, we will identify the links between physiological adaptation to higher temperatures and trade-offs in performance at lower temperatures. By determining the evolutionary changes in the carbon-fixing enzyme Rubisco’s physical and biochemical properties, we will address how the biochemical interdependence between enzyme stability and flexibility contributes to physiological performance and ecological requirements. Finally, by taking a mutational approach to directly test whether specific Rubisco amino acid replacements during Synechococcus evolution have conferred temperature adaptation and/or come with costs in performance at lower temperatures, we will have the rare opportunity to reveal the specific changes in molecules that shape ecology in a natural system. Together, these approaches will advance our understanding of the origins of microbial diversity by exploring physiological adaptation from genetic, structural and biochemical perspectives.

Diversity of arbuscular mycorrhizal fungi and soil aggregation

(Project PI, Matthias C. Rillig)

Soil aggregation (the arrangement of pore spaces and solid matter in soil) is a critically important process in natural and managed ecosystems, affecting a wide range of soil and ecosystem functions and biota. Management practices and erosion threaten soil structure on a national and global scale. Fungi, and in particular arbuscular mycorrhizal fungi (AMF), are of great significance in soil aggregation. However, we have almost no knowledge of the basic biological characteristics of AM fungi as they to soil aggregation. In this research, we are testing several fundamental biological (physiological and architectural) characteristics of AMF for their relationship with soil aggregation. We hypothesize that there are correlations of some fungal traits with soil aggregation across a number of fungal species. Our research also places soil aggregation in the context of other functions carried out by these symbiotic fungi, and we ask how different species of fungi can interact in maintaining stable soil aggregates.

Soil Charcoal and Nitrogen Cycling in Pinus ponderosa Ecosystems of Western Montana .

(Project PI’s B. Holben and T. DeLuca)

 Charcoal is a natural byproduct of wildland and prescribed fire and is well known as an important biochemical sorbent. Unfortunately, charcoal deposited during fire has received little scientific attention. Ponderosa pine forests are fire dependent ecosystems that are notoriously limited in productivity due to low nitrogen (N) availability. Fire results in a short-term increase in available N, but it appears that charcoal may dictate long-term N availability. We will determine whether charcoal directly or indirectly enhances forest N fertility. We will combine state-of-the-art soil microbiological and biochemical methodologies with fire history research plots (USDA-NRI project) to assess the influence of fire and fire exclusion on quantity and biophysical quality of charcoal. The experiments will provide the first ever look at charcoal as a mediator of nutrient dynamics in the Inland Northwest and are likely to have broad impact as fire and charcoal are common to all temperate ecosystems.