Dynamics of plasmid-containing cells in a chemostat under transient conditions

Simple item page
dc.contributor.advisorSan, Ka-Yiuen_US
dc.creatorWeber, Allison Elizabethen_US
dc.date.accessioned2009-06-04T00:46:06Zen_US
dc.date.available2009-06-04T00:46:06Zen_US
dc.date.issued1990en_US
dc.description.abstractOne of the major concerns in the utilization of plasmid-containing organisms in fermentation processes is the stability of the plasmid. In general, it is observed that two parameters, the probability of plasmid loss due to faulty segregation and the difference in the specific growth rate between the recombinant and reverted cells, govern the dynamics of the reactor. These parameters are affected by a number of factors: the genetic make-up of the host cells and the plasmid and the reactor operating parameters such as temperature, pH, dilution rate, and growth medium. It is speculated that by manipulating these factors it may be possible to enhance the stability of the plasmid-containing population. In this work the effects of well-defined perturbations in reactor conditions on plasmid maintenance and expression of a population of Escherichia coli K12 strain containing the plasmid pBR322 grown in a chemostat with a non-selective medium were studied. In a set of experiments the cultures were exposed to square-wave oscillations in the dilution rate. Under these conditions the cultures were capable of maintaining a mixed population of plasmid-containing and plasmid-free cells for a longer period of time than a culture grown under a constant dilution rate. The effect of the perturbations on plasmid copy number and expression were also studied. The data was dependent on the amplitude and frequency of the oscillations. In addition, the experiments indicate that adaptation of the culture to the transient conditions will reduce or totally eliminate any advantage created by the perturbations. An unstructured model, evaluating the probability of plasmid loss and the differences in the specific growth rate between the recombinant and reverted cells grown under dilution rate oscillations, was developed to describe the experimental data. The results indicate that the transient conditions provide a favorable environment for the plasmid-containing population. It was further observed, through the use of minimum inhibitory concentration experiments, that the plasmid-containing cells existed as a heterogeneous population with respect to the plasmid copy number. This population distribution could play an important role in plasmid stability and expression.en_US
dc.format.extent253 p.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.callnoTHESIS CH.E. 1990 WEBERen_US
dc.identifier.citationWeber, Allison Elizabeth. "Dynamics of plasmid-containing cells in a chemostat under transient conditions." (1990) Diss., Rice University. <a href="https://hdl.handle.net/1911/16404">https://hdl.handle.net/1911/16404</a>.en_US
dc.identifier.digitalWeberAen_US
dc.identifier.urihttps://hdl.handle.net/1911/16404en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectChemical engineeringen_US
dc.subjectBiochemistryen_US
dc.titleDynamics of plasmid-containing cells in a chemostat under transient conditionsen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentChemical Engineeringen_US
thesis.degree.disciplineEngineeringen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
WeberA.pdf
Size:
7.28 MB
Format:
Adobe Portable Document Format
Description:
Download
Collections
Rice University Theses and Dissertations