Immobilized cells: Plasmid stability and plasmid transfer

Barbotin, Jean‐Noël; Mater, Denis D.G.; Craynest, M.; Saucedo, J. E. Nava; Truffaut, Nicole; Thomas, Daniel

doi:10.1016/s0921-0423(98)80089-0

Cited by 8 publications

(10 citation statements)

References 88 publications

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“…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.…”

Section: Discussionmentioning

confidence: 99%

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

Unrean

Srienc

2010

Journal of Biotechnology

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We have developed highly efficient ethanologenic E. coli strains that selectively consume pentoses and/or hexoses. Mixed cultures of these strains can be used to selectively adjust the sugar utilization kinetics in ethanol fermentations. Based on the kinetics of sugar utilization, we have designed and implemented an immobilized cell system for the optimized continuous conversion of sugars into ethanol. The results confirm that immobilized mixed cultures support a simultaneous conversion of hexoses and pentoses into ethanol at high yield and at a faster rate than immobilized homogenous cells. Continuous ethanol production has been maintained for several weeks at high productivity with near complete sugar utilization. The control of sugar utilization using immobilized mixed cultures can be adapted to any composition of hexoses and pentoses by adjusting the strain distribution of immobilized cells. The approach, therefore, holds promise for ethanol fermentation from lignocellulosic hydrolysates where the feedstock varies in sugar composition.

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Section: Discussionmentioning

confidence: 99%

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

Unrean

Srienc

2010

Journal of Biotechnology

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“…These results suggest that cell immobilization can significantly improve the operational stability of poorlystable chromosomally-integrated recombinant strains. In previous studies immobilization has been shown to lead to improved operational stability with strains in which the recombinant genes are plasmid-borne (Barbotin et al, 1998;Chau et al, 2000;Chen et al, 2006;de Taxis du Poët et al, 1987;Zhang et al, 1996). This has been ascribed to various causes, including a reduced growth rate of the cells when immobilized (which would slow the rate of plasmid loss) and a reduced overall competition between P þ and P À cells due to their compartmentalization within the immobilizing agent (de Taxis du Poët et al, 1987).…”

Section: Discussionmentioning

confidence: 99%

“…Although there is no fully accepted explanation of why immobilization improves genetic stability, many investigators have shown that it increases plasmid stability in continuous cultures (Barbotin et al, 1998;Chau et al, 2000;Chen et al, 2006;de Taxis du Poët et al, 1987;Zhang et al, 1996). This is most likely due to its restriction of cell growth (as can alternatively be achieved by other means including nutrient limitation and manipulation of the environmental conditions).…”

Section: Introductionmentioning

confidence: 99%

Increased phenotypic stability and ethanol tolerance of recombinant Escherichia coli KO11 when immobilized in continuous fluidized bed culture

Zhou

Martin

Pamment

2008

Biotech & Bioengineering

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The recombinant Escherichia coli B strain KO11, containing chromosomally-integrated genes for ethanol production, was developed for use in lignocellulose-to-ethanol bioconversion processes but suffers from instability in continuous culture and a low ethanol tolerance compared to yeast. Here we report the ability cell immobilization to improve its phenotypic stability and ethanol tolerance during continuous culture on a 50 g/L xylose feed. Experiments conducted in a vertical tubular fermentor operated as a liquid-fluidized bed with the cells immobilized on porous glass microspheres were compared to control experiments in the same reactor operated as a chemostat without the support particles. Without cell immobilization the ethanol yield fell sharply following start-up, declining to 60% of theoretical after only 8-9 days of continuous fermentation. While immobilizing the cells did not prevent this decline, it delayed its onset and slowed its rate. With immobilization, a stable high ethanol yield (>85%) was maintained for at least 10 days, thereafter declining slowly, but remaining above 70% even after up to 40 days of fermentation. The ethanol tolerance of E. coli KO11 cells was substantially increased by immobilization on the glass microspheres. In ethanol tolerance tests, immobilized cells released from the microspheres had survival rates 2.3- to 15-fold higher than those of free cells isolated from the same broth. Immobilization is concluded to be an effective means of increasing ethanol tolerance in E. coli KO11. While immobilization was only partially effective in combating its phenotypic instability, further improvements can be expected following optimization of the immobilization conditions.

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“…high concentration of the gelling cations and use of copper instead of calcium cations. 21 This observation was the starting point of our investigation on the influence of a rigid shell on the formation of channel structures in the polysaccharide core. Core-shell microspheres with improved diffusivity inside the macroporous core can present intermediate properties between currently used core-shell systems and hollow shell microcapsules, extending the range of materials available for biocatalysis and drug delivery.…”

Section: Introductionmentioning

confidence: 95%

“…Radial shafts in the depth of the microsphere have been reported as another heterogeneity of alginate gels formed in the presence of copper cations or concentrated calcium cations. 21 A mechanism for the formation of capillaries normal to the gelation front has been proposed in the case of alginate gelation by divalent cations. [22][23][24] The mechanism of gelation implies a countercurrent diffusion of the solutions of the polysaccharide and the gelling agent.…”

Section: Introductionmentioning

confidence: 99%

Hierarchical Macroporosity Induced by Constrained Syneresis in Core−Shell Polysaccharide Composites

et al. 2005

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A radial pattern of macroscopic channels can be generated in core-shell polysaccharide microspheres during gel drying. The mechanical properties and the permeability of the outer crust can be tailored to control the formation of shafts in the organogel. The stiffness of the shell resists the shrinkage of the gel and causes channels to be opened in the direction in which the drying front advances. The permeability of the shell affects the effectiveness of supercritical drying and allows one to control the syneresis of the gel. Examples are provided from a chitosan-silica composite and from Cu-alginate gel beads with chemically modified outer crust.

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Immobilized cells: Plasmid stability and plasmid transfer

Cited by 8 publications

References 88 publications

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

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

Increased phenotypic stability and ethanol tolerance of recombinant Escherichia coli KO11 when immobilized in continuous fluidized bed culture

Hierarchical Macroporosity Induced by Constrained Syneresis in Core−Shell Polysaccharide Composites

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