Date of Award


Degree Type

Honors College Thesis

Academic Program

Biological Sciences BS


Biological Sciences

First Advisor

Mohamed Elasri, Ph.D.

Advisor Department

Biological Sciences


Staphylococcus aureus is a complex human pathogen that causes problems in both healthcare and community settings. Staphylococcus aureus is a gram-positive, sphere shaped bacterium that usually colonizes in the nasal cavity of healthy individuals. Staphylococcus aureus infections are a growing health concern due to its ability to produce virulence factors, such as pigmentation, protease production, and capsule formation. Two regulators in S. aureus virulence factors are msaABCR, which is a newly characterized operon, and ccpE. In order to determine the interaction between these two regulators in regulating virulence and metabolism in S. aureus, ccpE and ccpE/msaABCR transposon mutants were constructed. The ability for S. aureus to survive and adapt is due to its capability to reutilize acetate via TCA pathway, produce pigment and protease, and survive without access to nutrients and oxygen. Various assays such as aconitase activity assay, pigmentation assay, protease assay, and survival assay were performed in these strains and were compared to wild type and msaABCR mutant strains. Results from aconitase activity assays showed that msaABCR represses aconitase activity most likely via ccpE. Whereas, pigmentation assays and protease activity assays showed that msaABCR operon activate pigment production and repress protease expression independent of ccpE. In addition, we showed the role of ccpE in the stationary phase survival of S. aureus. This study thus elucidated the complex regulatory network of ccpE and msaABCR to determine virulence in S. aureus.