Plasmid Stability in Immobilized Mixed Cultures of Recombinant Escherichia coli

Abstract

The growth behavior of a mixed culture of plasmid-free and plasmid-containing (YEp352) Escherichia coli HB101 cells in free suspension and immobilized conditions was studied experimentally. It was found that immobilization in calcium alginate beads delayed the reduction of the plasmid-containing fraction for a period of time inversely related to the total number of cells initially immobilized. A simple unstructured model that assumes compartmentalization of cells in the immobilization matrix at the beginning of growth gave a fit which was in good agreement with the data.

Continuous production of ethanol from hexoses and pentoses using immobilized mixed cultures of Escherichia coli strains

“…The immobilized mixed cell cultures exhibited a high degree of operational stability when they were repeatedly used for several weeks without any loss of viability or ethanologenicity. The observed stability of immobilized cells may be contributed by the slowly- or non-growing state of cells when cells are immobilized (Barbotin et al, 1998; Chau et al, 2000; Dincbas et al, 1993; Najafpour, 1990). With the restricted growth of immobilized cells, the loss of genes or intracellular enzyme activity is minimized.…”

Kinetics and Stability of GM‐CSF Production by Recombinant Yeast Cells Immobilized in a Fibrous‐Bed Bioreactor

“…Cell immobilization has been used to overcome or alleviate plasmid instability problems and to enhance reactor productivity in recombinant cell fermentations (Barbotin, 1994; D'Angio et al, 1994; Dincbas et al, 1993; Joshi and Yamazaki, 1987; Kanayama et al, 1988; Nasri et al, 1987; Oriel, 1988; Sayadi et al, 1989; Sode et al, 1988; Walls and Gainer, 1991). In the immobilized cell system, the maintenance of a plasmid‐carrying cell population becomes easier as segregational plasmid loss and overgrowth of plasmid‐free cells are less likely to happen because of the reduced cell growth (Bailey et al, 1987; Walls and Gainer, 1989) and the compartmental cell distribution and mass‐transfer limitation in the immobilized cell environment (Barbotin et al, 1989; De Taxis du Poet et al, 1986; Dincbas et al, 1993). Immobilization also offers the advantage of providing high cell density and high reactor productivity and, thus, may be a preferable alternative to conventional free cells batch or chemostat processes.…”

Airlift-driven fibrous-bed bioreactor for continuous production of glucoamylase using immobilized recombinant yeast cells

“…11. Viability and fraction of plasmid-carrying cells in the immobilized phase of the fibrous-bed bioreactor after the 7th wash. bilized cell bioreactor and reduces the likely hood of segregational and competitive instability to occur (Walls and Gainer, 1991), (2) compartmental cell distribution and mass transfer limitation in the immobilized cell environment, thus limiting the overgrowth of the plasmid-free-cell population (Dincbas et al, 1993), (3) physiological changes in the immobilized cells and increased plasmid copy number at reduced growth rate, and (4) selective immobilization or preferential retention of plasmid-carrying cells in the fibrous bed (Zhang et al, 1997a,b;Yang and Shu, 1996).…”