AbstractsBiology & Animal Science

The Effects of Quorum Sensing on the Phenotypes of Pseudomonas Aeruginosa Bacteria Cells Within a Biofilm

by Stephanie Bissell

Institution: University of Akron
Department: Mathematics
Degree: MS
Year: 2011
Keywords: Mathematics; Microbiology; Pseudomonas aeruginosa; quorum sensing; biofilm; phenotype
Record ID: 1928629
Full text PDF: http://rave.ohiolink.edu/etdc/view?acc_num=akron1315840076


Pseudomonas aeruginosa is an opportunistic, gram-negative bacteria that targets individuals with compromised immune systems. This deadly bacteria is extremely resistant to antibiotics due to its ability to utilize quorum sensing to alter the phenotypes of its cells. The model presented uses advection equations to describe themixture of down-regulated, up-regulated, inert, and persister P. aeruginosa phenotypes within a biofilm. Diffusion equations are used to model soluble components of a biofilm, including the signaling molecules needed for quorum sensing. We assume that the conversion between down-regulated and up-regulated phenotypes is controlled by extracellular signaling molecules reaching a critical level. We also assume that the conversion between up-regulated and persister phenotypes depends on the concentration of nutrients within the biofilm. The work presented in this paper shows that by increasing the rates of conversion between down-regulated and upregulated phenotypes, we are able to decrease the population of down-regulated cells and increase the number of both up-regulated and persister cells in a growing biofilm. Altering the quorum sensing system within the bacteria cells will change the timing at which the different phenotypes reach equilibria but ultimately does not change the concentrations of the different cell phenotypes within a mature biofilm.