Optimizing a Method for Growing and Analyzing E.coli Biofilms to Investigate the Effect of theRpoF Transcription Factor on Biofilm Growth

Science Center, Bent Corridor

When put in contact with a surface, most gram-negative and gram-positive bacteria have the ability to adhere to the surface in the form of a film. This bacterial biofilm is made up of bacterial cells embedded in a matrix of proteins, nucleic acids, and polysaccharides. What makes bacterial biofilms particularly interesting is that the cells within them (termed sessile cells) are phenotypically and genotypically distinct from planktonic (free floating) cells. One important phenotypic difference is that sessile cells are more resistant to exogenous stressors such as antibiotics. This increased resistance to antibiotics presents a challenge when trying to prevent formation of biofilms on medical equipment and food. Our research is currently focused on optimizing methods for growing E.coli biofilms so that we can image them under a scanning electron microscope to observe major morphological changes in biofilm under different conditions of stress, as well as quantitatively measure biofilm growth via a microplate calorimetric assay. We are also investigating how the transcription factor RpoF (FliA) is involved in biofilm formation. RpoF controls the expression of genes associated with the construction of bacterial flagella, which are protein structures that directly determine bacterial mobility. Since biofilm formation requires bacterial cells to adhere to a surface and essentially stay put, a key step in biofilm formation is the loss of bacterial flagella. We are currently investigating how rpoF affects the rate and amount of biofilm formation by overexpressing rpoF in PHL628 E.coli cells.