Date of Award

Fall 2022

Degree Type


Degree Name

Master of Science (MS)


Microbiology and Immunology


Bacteria are complex social organisms that live within mixed communities where microorganisms compete for limited resources. We studied Contact-Dependent Growth Inhibition (CDI), a particular type of competition mediated by a type 5b, or two-partner, secretion system that is widely spread among Gram-negative bacteria. CdiB and CdiA make up the two-partner secretion system that mediates CDI. CdiB translocates CdiA to the cell surface, and CdiA delivers its C-terminal toxin domain to the target cell. The C-terminal toxin (Tox) domain of CdiA is highly diverse. We studied Tox domains of various Pseudomonas aeruginosa clinical isolates. We found different strains that contain unique CdiA-Tox domains differ in their ability to impart growth inhibition in bacterial competition. We determined this was not related to differences in the transcript level of cdiA but rather to inherent differences in the potency of Tox domains. This work provides insight into the complexities of interbacterial competition.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

Included in

Microbiology Commons