On plasmid population dynamics :spatial structure, mating pair formation and estimation of plasmid transfer rates


Zhong, Xue.. (2009). On plasmid population dynamics :spatial structure, mating pair formation and estimation of plasmid transfer rates. Theses and Dissertations Collection, University of Idaho Library Digital Collections.

On plasmid population dynamics :spatial structure, mating pair formation and estimation of plasmid transfer rates
Zhong, Xue.
Bioinformatics & Computational Biology
Plasmids play an important role in bacterial adaptation as these extrachromosomal genetic elements transfer between distantly related bacteria and benefit the hosts with plasmid-encoded traits such as antibiotic resistance. Plasmid transmission has been intensively studied, but theoretical developments have been mostly restricted to liquid environments. There is growing empirical evidence that transfer kinetics in surface-attached bacterial populations differs markedly from those expected in well-mixed liquid populations. Theoretically, this indicates a gap between traditional liquid-based models and surface-associated plasmid population dynamics. So far, only a few attempts have been made to close this gap. This work addresses this challenge by integrating empirical studies, model development and computer simulations to gain insights into plasmid transfer kinetics on solid substrates as well as their comparison to the liquid counterparts.;This work provides explanations for why plasmid spread on surfaces tends to be limited and why occasional mixing of the tells can greatly enhance plasmid spread. The reason is that host mixing promotes tell contact and resource access in the surface-attached bacterial communities. The work also yields a better understanding of how the presence of spatial structure affects our current estimation of plasmid transfer rates. The rate estimate of plasmid transfer in surface populations can be highly variable due to differences in the amount of contact between plasmid-bearing and plasmid-free tells. These findings were made with the development of individual-based models for simulating plasmid transfer dynamics on surfaces. Besides emphasizing the differences between surface and liquid environments, this work resolves confusion that arises from the discrepancies (> 8 orders of magnitude) observed in the values of the plasmid transfer rates between the two systems. To do so, a new differential equation model is developed that quantifies the rate of plasmid transfer in liquids using an 'intrinsic conjugation rate.' This model, in addition to capturing the profile of plasmid spread under shear forces, allows for comparisons of plasmid transfer rates between liquid and surface habitats within a unified framework.
Thesis (Ph. D., Bioinformatics and Computational Biology)--University of Idaho, June 2009.
Major Professor:
Stephen M. Krone.
Defense Date:
June 2009.
Format Original:
x, 85 leaves :ill. (some col.) ;29 cm.

Contact us about this record

In Copyright - Educational Use Permitted. For more information, please contact University of Idaho Library Special Collections and Archives Department at
Standardized Rights: