Meagan Mauter

Ph.D. Candidate, Chemical Engineering, Environmental Engineering Program, Yale University
M.S. Chemical Engineering, Environmental Engineering Program, Yale University
M.E.E., Environmental Engineering, Rice University, 2006
B.S., Magna Cum Laude, Civil and Environmental Engineering, Rice University, 2006
B.A., Magna Cum Laude, History, Rice University, 2006

E-mail: meagan.mauter@yale.edu

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My past research in the Elimelech Lab has focused on studying changes in E. coli transcriptome upon cell deposition and initial attachment to quartz surfaces. Specifically, I investigated the effect of the primary energy barrier on changes in cell transcript. Previous experiments in the Elimelech Lab have elucidated the role of the secondary energy minimum in determining bacterial adhesion and transport through porous media,¹ investigated the role of cell surface lipopolysaccarides in bacterial adhesion,² and have probed connections between motility features and deposition patterns using radial stagnation point flow systems.³ Although these results suggest that classic Derjaguin-Landau-Verwey-Overbeek (DLVO) theory effectively predicts bacterial deposition in ionic solutions, these experiments also suggest limitations in modeling bacteria as abiotic colloidal particles. Additional insight into the cellular processes and surface features impacting adhesion would aid in understanding discrepancies between theory and laboratory results.

My research has sought to contribute new insights into physiological changes that aid in bacterial deposition. Bacterial deposition is highly dependant on ionic strength conditions in the feed solution. Under conditions of low ionic strength, DLVO theory predicts the presence of a shallow secondary energy minimum and a large energy barrier to primary deposition. As ionic strength increases, this energy barrier diminishes and deposition rates are increased. To elucidate any impact that cellular functions might play in this increased deposition rate, I compared the response of bacterial physiology upon deposition at different energy barriers. Drawing on previous research for background knowledge and experimental design, I harvested cells from a series of column experiments at differing ionic strengths. DNA microarray was then used to analyze and compare resulting changes in the total cell transcript.

Preliminary results from the experiments reveal new insights into initial attachment of E. coli to abiotic surfaces. Most of the existing literature reports initial E. coli deposition and attachment under stagnant flow conditions. Under these conditions heightened biofilm formation is observed in bacteria expressing flagellar genes. These results have led researchers to prescribe a large role for flagella in the deposition process. For instance, Pratt and Kolter suggest that flagellar-mediated motility enables bacteria to initially reach a surface, perhaps by overcoming electrostatic repulsive forces.⁴ Under the continuous flow conditions in my research, however, a comparison of the total cell transcript between suspended and deposited cultures at high and low ionic strengths did not reveal up-regulation of flagella related genes. In fact, most of the flagella genes were either repressed or showed no change in expression. This suggests that flagella may not play a specific role in overcoming an energy barrier to deposition.

Although further experiments are necessary to confirm my results, this research may provide important insights into bacterial attachment to abiotic surfaces and biofilm formation. I am interested in expanding my knowledge of microbial communities and biofilm processes to better address these questions in complex biofilms.