Forney Lab: Stephen Bent

Introduction

The principle of competitive exclusion, which states that no two species can occupy precisely the same niche for an indefinite period of time, has been central to the modeling and understanding of ecosystems for many years.  Spatial heterogeneity, such as that found in soil and sediment environments, may be a factor in relaxing competitive interactions, and thus allowing persistence of multiple strains of bacteria using the same resources, but spread across many spatially separated microhabitats.

Experimental Approach

My first study involved analysis of samples taken from the corners and center of a one meter square of wetland sediment.  I analyzed the population structure of the culturable purple non-sulfur bacteria in these samples, and determined that multiple strains of the same species could exist in a small (0.5 gram) sample of sediment, and that the distribution of strains was not correlated with distance at that scale.

I am using the physiological similarity of strains within a species to establish microcosm experiments in which several genetically distinct strains of Shewanella putrefaciens compete for the same limiting resource in column reactors packed with glass beads under continuous flow conditions.  By assessing the final relative proportions of the strains that were initially inoculated in the columns in the context of characterized growth rates for the strains, we can gain an understanding of whether spatial heterogeneity by itself is sufficient to allow for maintenance of diversity among strains with similar metabolic characteristics.  By incorporating mathematical modeling techniques, I intend to develop and apply a predictive mathematical framework to guide our understanding of the effects of spatial heterogeneity on microbial interactions and diversity.

Education

B.A. Cornell University, Physics and Biology, 1992

Publications

Bent, S. J., C. L. Gucker, Y. Oda, and L. J. Forney. 2003. Spatial distribution of Rhodopseudomonas palustris ecotypes on a local scale. Appl. Environ. Microbiol. 69:  (in press)

Shyu, C., T. Soule, S. J. Bent, J. A. Foster, and L. J. Forney. 2004. MiCA: A Web-Based Tool for the Analysis of Microbial Communities Based on Terminal Restriction Fragment Length Polymorphisms (T-RFLP) of 16S and 18S rRNA Genes. (in manuscript)

Zhou, X., Bent, S. J., Schneider, M. G., Davis, C. C., Islam, M, R., and Forney, L.J. 2003. Characterization of vaginal microbial communities in adult healthy women using cultivation-independent methods. (in preparation)

Zhou, X., S. J. Bent, G. M. Schneider, C. C. Davis and L.J. Forney. 2003. Is Atopobium vaginae a predominant member in vaginal microbial communities of healthy women. (in preparation)