Date of Award
Doctor of Philosophy (PhD)
Martin A. Hjortso
Specific cell adhesion was proposed as a means to separate and selectively remove or recycle a population in a mixed culture reactor. Theoretical analysis indicated that stable coexistence steady states of competitive mixed cultures and unstable recombinant cultures are possible with this method. Specific cell adhesion was used to separate populations of Escherichia coli based on their expression of maltoporin an outer membrane protein. This separation was possible due to maltoporin binding immobilized starch. Various methods for operating a packed bed of the immobilized starch support are reported. Operating conditions are identified that allow quantitative estimates of populations based on their expression of functional maltoporin. This system was used as a means of obtaining real time estimates of the population balance in mixed culture fermentations. Specific adhesion was incorporated in a reactor designed to separate and selectively recycle strains of E. coli and allowed direct of the mixed culture population balance. The selective release of specifically adhering cells was addressed as a method of separating cell populations. A discrete kinetic model was developed for the binding and release of the receptor-ligand pair on an adhering cell. Various factors including receptor and immobilized ligand density, removal forces, receptor-ligand binding kinetics, receptor mobility and soluble competing ligands were incorporated into this framework. The effect of these parameters on fractionation of cell populations based on receptor expression was investigated. Several analytical solutions for the dynamic model of cell release were developed for limiting cases. One of these models was used to successfully predict the release of specifically adhering cells from a packed bed.
Roos, Joseph William, "Specific Cell Adhesion and Its Application to Monitoring and Control of Mixed Culture Bioreactors." (1990). LSU Historical Dissertations and Theses. 4950.