Yue Cheng Zhu

Date of Award


Degree Type


Degree Name

Master of Science


Microbiology and Immunology


Dr. Martin McGavin


Staphylococcus aureus is implicated in many different infections and is known to readily build biofilms on host tissues and biological implants, leading to numerous transplant and implant related complications every year. Its proteases, especially those encoded by the sspABC operon, may play a role in biofilm dispersal and are the focus of this study. A protease-deficient mutant of S. aureus was constructed through allelic replacement of the sspABC operon, and the resulting mutant was used to assess changes in vitro and in vivo through biofilm growth assays under various conditions of acid stress and carbon source supplementation, and in a murine bacteraemia model. Deletion of the proteases of sspABC operon led to increased thickness of biofilm mat and formation of large aggregations of bacterial communities. In the murine abscess model, deletion of proteases of the sspABC resulted in no significant differences in overall virulence despite possible differences in bacterial distribution



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