Modeling of plasmid dynamics and persistence in a community of hosts

Martins, Sonia Cristina Santos (2013). Modeling of plasmid dynamics and persistence in a community of hosts. University of Birmingham. Ph.D.

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Abstract

Some bacterial plasmids have a narrow (NHR) while others have a broad host-range (BHR), facilitating the propagation of antibiotic resistance genes through natural communities. An extended host-range should mean less adaptation to any particular host and this should result on average, in a greater fitness burden for its hosts.Thus, what are the advantages of having a broad host-rage? The dynamics of transfer of BHR plasmids competing with faster growing NHR-plasmid bearing cells in two-species assemblages in chemostats and biofilms was analysed using mathematical models. In chemostats a costly NHR plasmid that can survive in a single species population could not survive in a two-species assemblage. Adding a BHR competitor helps the NHR plasmid to survive and coexistence of both plasmids becomes possible if ttre plasmids are incompatible. In two-species biofilms the BHR plasmid is the better competitor despite the higher costs, whereas NHR spreading is severely hindered by biofilm patchiness. Experimentally, mating experiments and growth curves showed a strong dependency of plasmids transfer frequency and fitness burden on species background. Overall, this work demonstrates how competition, differences in host-range and compatibility relationships between plasmids can enhance the chances of plasmid persistence in two-species assemblages.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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