Research Description:
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Microbial biofilms: understanding microorganisms attached to surfaces
The central focus of research in my laboratory is microbial biofilms, or communities of microorganisms attached to surfaces. Biofilms are widely distributed in nature, and may be beneficial or harmful to humans, depending on the microbes that inhabit them. A common feature to all of our work with biofilms is quantitative analysis of biofilm structure based on biofilms grown in flow cells and imaged by confocal microscopy. This approach allows us to make rigorous examinations of factors affecting biofilm structure, organization and function.
Recent projects
In one project, we found that plant essential oil components can affect biofilm formation, and determined that the plant-derived compound cinnamaldehyde inhibited select types of bacterial quorum sensing, or cell-to-cell communication. A related project determined that expression of luxS, the gene encoding autoinducer-2 (AI-2) synthase, altered biofilm structure and cell fimbriation. A second avenue of research in our laboratory is directed towards understanding cooperative interactions in multispecies biofilms. Using a model system, we investigated a commensal relationship where an antibiotic resistant strain of E. coli could aid the survival of an antibiotic sensitive strain, and found that the benefit was conditional, depending on antibiotic concentration. We are currently using the model to investigate mutualistic interactions that contribute to multiple antibiotic resistance. In a third project that diverged from our work on cooperative interactions, we found that biofilms improved the maintenance of high copy number plasmids and also the production of heterologous protein relative to cells in suspended culture. This novel finding could be a beneficial tool for use in metabolic engineering.
Current research
We are currently working on approaches to cultivate multispecies biofilms with defined compositions. We hope to use our newly-developed techniques in our research on cooperative interactions that foster antibiotic resistance, and to build multispecies biofilms that break down mixed wastes.
To learn more about us, please visit our website.
Recent Publications:
O'Connell, H. A., C. Niu and E. S. Gilbert (2007). "Enhanced high copy number plasmid maintenance and heterologous protein production in an Escherichia coli biofilm." Biotechnol Bioeng. 97(3): 439- 446.
O'Connell, H. A., G. S. Kottkamp, J. L. Eppelbaum, B. A. Stubblefield, S. E. Gilbert and E. S. Gilbert (2006). "Influences of biofilm structure and antibiotic resistance mechanisms on indirect pathogenicity in a model polymicrobial biofilm." Appl Environ Microbiol 72(7): 5013-9.
Niu, C., S. Afre and E. S. Gilbert (2006). "Subinhibitory concentrations of cinnamaldehyde interfere with quorum sensing." Lett Appl Microbiol 43(5): 489-94.
Niu, C., J. Graves, F. Mokuolu, S. E. Gilbert and E. S. Gilbert. 2005. Enhanced swarming of bacteria on agar plates containing the surfactant Tween 80. Journal of Microbiological Methods. J Microbiol Methods 62:129-32.
Belkasim, S., J. Gu, G. Derado, E. Gilbert, H. O'Connell 2004. Multi resolution image segmentation for quantifying spatial heterogeneity in mixed population biofilms, p. 197-203. The 2004 International Conference on Mathematics and Engineering Techniques in Medicine and Biological Sciences (METMBS '04), Las Vegas, NV, USA.
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