Randal Fox, Top Lab Alum
Former Graduate Student, M.S. Microbiology, May 2007

…Research

I have worked on two different projects in the laboratory of Dr. Eva Top

Evolution of an unfavorable plasmid-host association

The plasmid pB10 is a broad-host-range antibiotic resistance plasmid with the ability to transfer to and replicate in most Gram-negative bacteria. It has been shown that pB10 has been stably maintained in several species in the absence of antibiotics. My work was to view whether there are some Gram-negative species that are not well adapted to pB10, or in other words, species in which pB10 is less stable or has a high cost. I isolated transconjugants from various habitats and determined that plasmid pB10 showed a low stability and a high cost in a P. putida strain, designated H2. Strain H2 with pB10 was evolved in medium with antibiotics for 1000 generations. After 1,000 generations, the stability of the evolved plasmids in the ancestral host had increased and the metabolic burden decreased (Heuer et al., 2007).

Invasion of a plasmid free population of E. coli by plasmid pB10.

For my Masters's research, I study the ability of IncP-1 plasmids to invade plasmid-free bacterial populations. We are investigating how spatial structure is a key determinant in the spread and persistence of antibiotic resistance plasmids in bacterial populations, and how stochastic cellular automata models can accurately predict the resulting behavior. My goal is to examine the effects of nutrients and spatial structure on the invasion of the multi-resistance plasmid pB10 on agar plates. Invasion is defined as a significant increase in the fraction of plasmid-containing cells over time. Results show that invasion occurs in E. coli K-12 under certain environmental conditions.

…Publications

Holger Heuer, Randal E. Fox, Eva M. Top. Frequent conjugative transfer accelerates adaptation of a broad-host-range plasmid to an unfavourable Pseudomonas putida host. FEMS Microbiol. Ecol. 59: 738-748.

Stephen M. Krone, Ruinan Lu, Randal E. Fox, and Eva M. Top. 0Modeling the Spatial Dynamics of Plasmid Transfer and Persistence. (Microbiology, in revision).

…Presentations - posters

Randal E. Fox and Eva M. Top. Invasion of a plasmid free population of E. coli by the IncP-1β plasmid pB10. 2006 Plasmid Biology Meeting in Lake Tahoe

Eva M. Top, Ruinan Lu, Randal Fox, and Stephen M. Krone. Modeling the Spatial Dynamics of Plasmid Transfer and Persistence. 2006 Northwest Branch Meeting of the American Society of Microbiology in Seattle, WA.

Randal E. Fox, Eva M. Top. Invasion of a plasmid free population of E. coli by plasmid pB10. 2006 Northwest Branch Meeting of the American Society of Microbiology in Seattle, WA.

Randal Fox, Holger Heuer, Eva M. Top. Rapid coevolution of a broad-host-range antibiotic resistance plasmid with its bacterial host. 2004 COBRE External Advisory Committee Meeting in Moscow, Idaho.

Randal Fox, Holger Heuer, Eva M. Top. Rapid coevolution of a broad-host-range antibiotic resistance plasmid with its bacterial host. 2004 Idaho BRIN/INBRE Annual Meeting in Pocatello, Idaho.

Randal Fox, Holger Heuer, Eva M. Top. IncP-1 plasmid pB10 is unstable and costly in P. putida H2. 2003 COBRE External Advisory Committee Meeting in Moscow, Idaho.

Randal Fox, Holger Heuer, Eva M. Top. IncP-1 plasmid pB10 is unstable and costly in P. putida H2. 2003 Northwest Branch Meeting of the American Society of Microbiology in Vancouver, Canada.