David Anthony Rivetti



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A biofilm is a group of microbes that are found in hydrated matrices of cells and contain polysaccharides, extracellular DNA, and proteins. Bacteria growing in biofilms are often resistant to antimicrobial treatments and are able to go undetected by the immune system of their host if located within a host organism. Microorganisms that form biofilms have the potential to colonize all higher organisms and contaminate biomedical implants, leading to further complications. As a result of their physical and chemical properties, biofilms are difficult to break down and separate from their surfaces. With the increasing problem of antibiotic resistance, there is a need to further consider different treatment options to combat biofilm growth. Cationic porphyrins have the capacity to cause DNA damage in a biofilm by intercalating between the base pairs of a DNA sequence, resulting in the breakage of the strand. Certain porphyrins can be used in the absence of light, while others require photoactivation in order to achieve their optimal effects. In order to further develop a comprehensive treatment method and identify other uses for the porphyrins, additional substrata must be tested in order to determine if porphyrins can be utilized as a viable treatment option. The substrata considered include metal (stainless steel, a biomedical implant material), polyethylene (kidney dialysis tubing material), oyster shell (an easily fouled environmental surface), and glass. TMP, or 5,10,15,20-tetrakis (1-methyl-pyridino)-21H,23H-porphine, tetra-p-tosylate salt, and a novel zinc porphyrin were introduced to the Pseudomonas aeruginosa biofilms on the various substrata to test for efficacy in disruption of a formed biofilm as well as inhibition of biofilm growth on the substrata. In both cases, a reduction in biofilm growth was observed following viable plate counts and confocal image analysis.

Publication Date


Project Designation

Honors Thesis

Primary Advisor

Karolyn M. Hansen, Jayne B. Robinson

Primary Advisor's Department



Stander Symposium project

Inhibition and Prevention of Biofilm Growth: The Effect of a Cationic and  Novel Zinc Porphyrin on Pseudomonas aeruginosa Biofilm Formation on Different Substrata