DESCRIPTIONS OF POTENTIAL PROJECTS

Project: Time-series Evolution of Tertiary Structures in Bacterial Biofilms

Research Mentor :  M.M. Baum


Bacteria possess the ability to adhere to surfaces and grow within an extracellular matrix of their own synthesis. Although these bacterial aggregates, or biofilms, were first identified in natural aquatic environments, their importance in infectious disease is attracting much attention. For pathogens, life in a biofilm offers protection from mucociliary clearance and phagocytosis as well as from antibiotic attack thereby playing a participatory role in persistent infections. Recently, we found that a series of axenic Pseudomonas spp. strains, isolated from a local field site, produced copious amounts of biofilm. Examination of biofilm structures by scanning electron microscopy (SEM) revealed remarkable three-dimensional architectures consisting of dense, fibrillary clusters and ordered, honeycomb-like chambers enveloped in thin sheets. These tertiary structures were populated by living and dead bacteria.

The next phase of this research will involve studying the biofilm morphology as a function of bacterial growth conditions. Biofilms for a range of cultures will be sampled at regular time intervals and examined by SEM. Chemical characterization of the extracellular polymeric substances (EPS) making up the biofilms also will be carried out. Compositional analysis of the EPS (predominantly carbohydrates) will be carried out using established procedures. Freeze-dried biofilm samples –obtained by rapid freezing and freeze substitution techniques also used in preparing samples for examination by SEM– will be deuterium-exchanged by repeated evaporation from CH3OD and dissolved in DCl/D2O for analysis by 1H NMR spectroscopy. Experience in microbiology, particularly aseptic technique, and 1H NMR spectroscopy will be considered as a plus.