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Arnold School of Public Health


Research

Our laboratory centers on understanding the roles of microbial biofilms in marine, environmental and health related processes.  We conduct fundamental research in order to understand how biofilms function, and ultimately can be controlled in environments and disease.

The matrix of extracellular polymer secretions (EPS) that surround bacteria is the key and defining attribute of biofilms. Biofilms exhibit a high level of organization, and 3D microphysical architecture, and cell-to-cell chemical communication networks. This allows bacteria to act as coordinated groups of cells, and facilitates greater metabolic efficiency and flexibility. The unique properties of EPS are instrumental in this organization. EPS localizes chemical signaling (i.e. quorum sensing), antibiotics, extracellular enzymes; and conserves water during desiccation (i.e. water loss). Together, the EPS underlies the adaptability and resiliency of biofilms in both natural systems and hospital-disease settings. 

Our laboratory probes biofilms under in-situ and manipulated conditions. In our research, we utilize various chemical/biological analyses as well as non-destructive spectroscopic and imaging techniques including confocal scanning laser microscopy (CSLM), scanning- (SEM) and transmission- (TEM) electron microscopy, atomic force microscopy (AFM), NMR, Infared- (FT-IR) and Raman-spectroscopy. The interdisciplinary nature of our research has provided interesting collaborations with colleagues in chemistry, marine sciences, biology, geology, engineering and medicine. 

Research Priorities    

Fundamental properties of extracellular (EPS) matrices under different environmental- and infection- conditions. Organization of the biofilm matrix and extracellular activities depend upon EPS. Our studies are investigating: (1) compositions, functional groups, and pore-spacing between adjacent EPS polymers; (2) how certain EPS form a glass state to protect extracellular molecules during desiccation; and (3) how EPS may promote or inhibit precipitation of calcium carbonate (CaCO3); an important sink for CO2 in climate change.   

Bacterial cell-cell communication (quorum sensing) within biofilms:  Quorum sensing (QS) allows bacterial cells to cooperatively conduct group activities through coordinated gene expression. It contributes important roles in infections through secretion of virulence factors, extracellular enzymes that hydrolyze antibiotics, and other activities. We are studying QS signaling with microbial mats, how QS signals travel within EPS, and how they are protected by components of EPS during desiccation.

Infection control: isolating novel antibiotics from unique microbial systems and designing unique antimicrobial polymers. We are isolating and characterizing novel antibiotics from bacteria in microbial mats. We are also exposing bacteria to unique stresses and stimulating the silent genome of bacteria. We also collaborate with chemists to design antimicrobial polymers, which inhibit antibiotic degrading enzymes (beta-lactamases), and in doing so, will enhance the efficacy of existing antibiotics.   

Engineered Nanoparticles for Combatting Infections Nanoparticles (NP) are incredibly small (1-100 nm). However, they have unique physical and chemical properties and can be chemically altered to carry drugs. At present, we are using nanoparticles as ‘Antibiotic Delivery Vehicles’ (ADV) to enhance the potency of present-day antibiotics. We are attempting to understand how surface properties of NPs may be altered to better penetrate biofilm EPS and more efficiently destroy infections.