Master of Science (MS), Bowling Green State University, 2021, Biological Sciences

Pharmaceutical companies have slowed the discovery and development of antibiotics due to low-profit margins. Therefore, antibiotic discovery is at an all-time low, and pathogens have evolved resistance to all currently available drugs. As a result, multi-drug resistant (MDR) bacterial infections are becoming more difficult to treat, especially in individuals at a high risk for infection such as cystic fibrosis (CF) patients. CF is a genetically inherited disease that inhibits or decreases chloride ion transport across epithelial cell membranes, resulting increased mucus viscosity, impairing normal clearance in the lungs. This environment is ideal for bacterial colonization and leads to a chronic lung infection. A major pathogen that colonizes the CF lung over time is Pseudomonas aeruginosa. A promising alternative treatment against MDR P. aeruginosa is bacteriophage therapy which has several advantages compared to antibiotics. First, phage therapy exhibits minimal side effects because phage are highly host-specific and do not inhibit other bacteria that are part of the human microbiome. Second, phage replicate itself exponentially when killing its host; and third, phage can be applied directly to the site of infection. However, like antibiotics, bacteria can evolve resistance to phage. To circumvent the problem of phage and drug resistance, trade-off effects may promote opportunities against both entities that may be exploited to treat MDR infections. I hypothesize that the effectiveness of antibiotics can be restored after selective pressure from bacteriophage. To test this hypothesis, MDR P. aeruginosa strains were exposed to phage in trade-off experiments, and results showed that the evolved phage resistant P. aeruginosa strain became antibiotic susceptible. In one trade-off experiment, a temperate phage recombined in the P. aeruginosa pathogen at a location downstream of a multidrug resistance efflux pump that may directly affect antibiotic susceptibility. In an (open full item for complete abstract)

Committee: Hans Wildschutte Ph.D (Advisor); George Bullerjahn Ph.D (Committee Member); Ray Larsen Ph.D (Committee Member) Subjects: Bioinformatics; Biology; Biomedical Research; Microbiology; Molecular Biology

MS, University of Cincinnati, 2011, Engineering and Applied Science: Biomedical Engineering

Artificial molecular motors have been an emerging research field in the last two decades. In this project we designed a novel functional vesicle system on the basis of a unique motor protein, the efflux transporter AcrB, and a photosensitive proton pump Bacteriorhodopsin (Br). Protein-containing lipid vesicle formation is a self-assembly process, with size distribution being verified by dynamic light scattering experiments. Proteins are incorporated into the lipid membrane to form a functional system that converts external photon energy into a proton motive force which is used by AcrB to actively pump substrates into the vesicle interior. The pumping performance of the designed vesicle system is quantitatively evaluated using Ethidium Bromide and the antibiotic substrate Bocillin. The active pumping rate is 0.01nmol/mg/s, which is comparable to current data from bacterial cell in vivo experiments. The addition of intravesicular nanodiamonds and linking AcrB with Br will further enhance the pumping ability and capacity of the total system, while adding an AcrB blocker will disable the pump and serve as a negative control. Furthermore, a theoretical model is constructed that can explain the different pH gradients for four types of vesicle systems and estimate the functionality of the system from the aspect of thermodynamics. The designed vesicle system is of great use for bioremediation, environmental health etc, and provides us with some useful clues for the further advancement of molecular machinery.

Committee: David Wendell PhD (Committee Chair); Dionysios Dionysiou PhD (Committee Member); Andrew Herr PhD (Committee Member) Subjects: Biomedical Research