Michelle L. Gee

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Twitching motility-mediated biofilm expansion is a complex, multicellular behavior that enables the active colonization of surfaces by many species of bacteria. In this study we have explored the emergence of intricate network patterns of interconnected trails that form in actively expanding biofilms of Pseudomonas aeruginosa. We have used high-resolution,(More)
Force spectroscopy using the atomic force microscope (AFM) is a powerful technique for measuring physical properties and interaction forces at microbial cell surfaces. Typically for such a study, the point at which a force measurement will be made is located by first imaging the cell using AFM in contact mode. In this study, we image the bacterial cell(More)
Antimicrobial peptides hold promise as broad-spectrum alternatives to conventional antibiotics. The mechanism of action of this class of peptide is a topical area of research focused predominantly on their interaction with artificial membranes. Here we compare the interaction mechanism of a model antimicrobial peptide with single artificial membranes and(More)
The interactions of bacteria with their environment are governed by a complex interplay between biological and physicochemical phenomena. The main challenge is the joint determination of the intertwined interfacial characteristics of bacteria such as mechanical and hydrodynamic softness, interfacial heterogeneity, and electrostatic properties. In this(More)
The interaction of a melittin mutant with a 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC)-supported lipid bilayer was studied with the use of time-resolved evanescent wave-induced fluorescence spectroscopy (TREWIFS) and evanescent wave-induced time-resolved fluorescence anisotropy measurements (EW-TRAMs). The mutant peptide was labeled at position(More)
The mechanism of interaction between a model antimicrobial peptide and phospholipid unilamellar vesicle membranes was studied using fluorescence spectroscopy, fluorescence lifetime measurements, and light scattering. The peptide, a mellitin mutant, was labeled at position K14 with the polarity-sensitive probe AlexaFluor 430. The kinetics of the interaction(More)
The interaction dynamics between a lytic peptide and a biomembrane was studied using time-lapse fluorescence lifetime imaging microscopy. The model membrane was 1,2-dipalmitoyl-sn-glycero-3-phosphochloine giant unilamellar vesicles (GUVs), and the peptide was the K14 derivative of melittin, to which the polarity-sensitive fluorescent probe AlexaFluor 430(More)
Bacterial biofilms are complex multicellular communities that are often associated with the emergence of large-scale patterns across the biofilm. How bacteria self-organize to form these structured communities is an area of active research. We have recently determined that the emergence of an intricate network of trails that forms during the twitching(More)
We have shown that the molecular conformation of a protein at an interface can be probed spatially using time-resolved evanescent wave-induced fluorescence spectroscopic (TREWIFS) techniques. Specifically, by varying the penetration depth of the evanescent field, variable-angle TREWIFS, coupled with variable-angle evanescent wave-induced time-resolved(More)
Bacteria form biofilms to facilitate colonization of biotic and abiotic surfaces, and biofilm formation on indwelling medical devices is a common cause of hospital-acquired infection. Although it is well-recognized that the exopolysaccharide capsule is one of the key bacterial components for biofilm formation, the underlying biophysical mechanism is poorly(More)