Available at: http://digitalcommons.calpoly.edu/theses/816
Date of Award
MS in Biomedical Engineering
Biomedical and General Engineering
Daniel W Walsh
Bacteria are among the most abundant microorganisms on earth, and can be found in essentially every environment. When a clean surface is exposed to media containing planktonic bacteria, the bacterial cells will attach to the surface and aggregate to form what is known as a biofilm. Biofilms have been shown to negatively affect many industries including medical, industrial, and food science applications. While biofilms have been well characterized from a microbiology perspective, there has been much less research from a materials science standpoint. It is hypothesized that the material properties of the substratum (such as the micro-structure) have a significant impact on biofilm growth. To research this hypothesis, protocol was established in order to produce, analyze, and study biofilms in a static exposure system. Though simple, the static bioreactor was proved to be adequate for inducing microbial attachment to processed samples. Methodologies for analyzing the established biofilms were presented, and an experimental procedure was proposed that enables the correlation of material properties to microbial growth on the substratum. The experimental procedure utilized Design of Experiments in a three factor, two level study that identified the interaction of Material Composition, Surface Conditions, and the Effect of Welding on microbial growth. In a trial iteration of the experiment, samples of 303 and 304 Stainless Steel were mounted in Bakelite and processed. Some samples were sanded to 600 grit sand paper, while others were polished to 1µm. The samples were exposed to biologically active natural water and imaged with scanning electron microscopy. Preliminary results were presented, and limitations of the study were identified.