Date of Award

Spring 2008

Document Type

Restricted Thesis

Terms of Use

© 2008 Kathleen Condon. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts


Biology Department

First Advisor

Amy Cheng Vollmer


Biofilms are complex surface associated communities of bacteria. Bacteria in biofilms secrete an extracellular matrix important for adhesion, protection and structure. Cells in biofilms have greater resistance to environmental stressors than free-floating planktonic cells. To better understand how biofilms respond to stress, the role of the universal stress protein A in Escherichia coli biofilm formation was investigated. Mixed biofilms were constructed with a wild type and uspA-null mutant, each expressing a different color fluorescent protein and viewed with a confocal laser scanning microscope. These methods were used in an effort to understand differences in biofilm formation between the two strains. A second set of experiments examined the effect of low levels of antibiotics on biofilm formation. Previous research has suggested that sub-inhibitory, low levels of antibiotics may increase bacteria virulence, biofilm formation and alter motility. The effect of a variety of antibiotics (at low concentrations) on biofilm formation and swimming motility for the wild type and uspA null mutant was investigated. Previous research and the findings presented here may suggest that antibiotics are important for bacterial communication.