Date on Master's Thesis/Doctoral Dissertation


Document Type

Master's Thesis

Degree Name




Degree Program

Biology, MS

Committee Chair

Yoder-Himes, Deborah

Committee Co-Chair (if applicable)

Perlin, Michael

Committee Member

Demuth, Donald


Bacterial genetics


We are constantly surrounded by bacteria, many of which are found in cohabitation with other species in the same niches. These organisms can be particularly problematic when they infect the human body. Cystic fibrosis (CF) is of significant concern because of the frequency that those suffering from this autosomal recessive disease have in colonization by these infectious agents. Affecting more than 30,000 people in the U.S. alone. CF is due to a genetic mutation that causes a thick mucosal buildup in luminal surfaces. This viscous mucus creates a cultivation site for complex respiratory biofilms. Complications of CF include paralysis of respiratory cilia and an inability to absorb nutrients in the digestive tract. The study of these bacteria in mixed communities, which better represents their common modes of infection, is critical to understanding the mechanisms of virulence for these pathogens. Studying poly-microbial biofilm-forming organisms in monoculture has intrinsic inaccuracies. In this work, the phenotypes of opportunistic respiratory pathogens were observed in co-culture growth. P. aeruginosa 2192, Pseudomonas aeruginosa PAO1, S. maltophilia K279a, Burkholderia dolosa AU0158, B. cenocepacia K56-2 and Escherichia coli pEBFP showed limited growth defects when spotted proximally in pairwise comparisons, but when testing effects of their growth on established bacterial lawns, inhibitions were more pronounced. The transcriptome of P. aeruginosa 2192 and S. maltophilia K279a were characterized in in mono- or co-cultures in three in vitro conditions using high-throughput Next-Gen Sequencing. This resulted in hundreds of significant changes in gene expression which indicate that these two CF pathogens can sense and respond to each other. Of the genes up-regulated in S. maltophilia K279a in response to growth with P. aeruginosa 2192, seven constructs were made for future complete gene deletion generation. This work provides a model where genes up-regulated in response to mixed communities can be identified and complete gene deletions can be made for future co-culture growth experiments.

Included in

Biology Commons