Immobilized Bacteria and Plasmid Stability

Iniesta, F. Marín; Poët, P de Taxis du; Dhulster, Pascal; Thomas, Daniel; Barbotin, Jean‐Noël

doi:10.1111/j.1749-6632.1987.tb45729.x

Cited by 11 publications

(1 citation statement)

References 35 publications

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“…Age of the microbial culture, its oxygen requirements, and the nature of the substrate can also have important effects. In contrast to gel supports, microorganisms on porous, solid supports such as Celite or glass have been observed to form irregular groups or thin films on the outer surface of the support .1,2, 6,8 Using L. mesenteroides immobilized in calcium alginate or Celite beads for production of dextransucrase and dextran, we noted a mass-transfer limitation attributed to the dextran formed inside or on the surface of the support. This affected the release of soluble dextransucrase (DS) from inside the support to the fermentation medium, especially with cells immobilized in calcium alginate bead^.^-^ This article describes the use of sintered, porous, stainless steel to support the growth of L. mesenteroides during the long-term, direct production of dextran in batch fermentation processes.…”

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confidence: 80%

Investigation of production of dextran and dextransucrase by Leuconostoc mesenteroides immobilized within porous stainless steel

El-Sayed

Abdul-Wahid

Coughlin

1992

Biotech & Bioengineering

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Cells of Leuconostoc mesenteroides were immobilized within porus, stainless-steel (SS) supports and used for dextransucrase (DS) and dextran production. The pore size of the support significantly affected the dextran yields, which were greatest with average pore sizes of 2-5 microm. All immobilized-cell biocatalysts in porous stainless steel produced higher yields than free cells, with the exception of cells confined in submicrometer pores (0.5 microm). Coating supports of larger pore size (40 and 100 microm) with calcium alginate enhanced the cell-loading capacity of the supports and increased dextran and fructose yields in the cell-free broth. Controlled, fed-batch, DS production (activation), as a step preliminary to dextran production, significantly improved the subsequent dextran and fructose yields and shortened the time required to attain the maximum such yields. Scanning electron microscopy (SEM) of immobilized L. mesenteroides in stainless steel shows an irregular pattern of the microorganism inside the pores of the solid supports. Coating the porous solid supports with a cell-free calcium alginate layer led to an increase in the cell density inside the support. Cell growth inside the coated, porous stainless steel had no distinct growth form.

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Section: Introductionmentioning

confidence: 80%

Investigation of production of dextran and dextransucrase by Leuconostoc mesenteroides immobilized within porous stainless steel

El-Sayed

Abdul-Wahid

Coughlin

1992

Biotech & Bioengineering

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Kinetic study of pTG201 plasmid stability in Escherichia coli

Marín-Iniesta

1988

Acta Biotechnologica

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Recombinant pTG201 plasmid coming from pBR 322 plasmid, has been incorporated into Escherichia cola K12 to determine the influence of several culture conditions on the variation of the copy number. Continuous and batch cultures on LB medium without antibiotic selection and different oxygen tensions (21% and 100%) have been tested. The expression of pTG201 encoded genes and the kinetics of plasmid loss differ significantly from the behaviour of pBR322 plasmid. Int-roductionPlasmids are useful instrunients for Genetic Engineering so nowadays it is possible the cloning and expression of foreign DNA in bacteria for objectives such as industrial production of plasmid encoded proteins. However, after overcoming the difficulties of cloning and expression, the problem of instability of the recombinant plasmids appears and the use a t industrial level of such systems can be infeasible. This is obvious with pTG201 plasmid that was used as experimental model to study the instability of recombinant plasmids. This pTG2Ol plasmid derivates from pBR322 where genetic material from 1 phage and Pseudomoms putida was inserted [1,2]. As a consequence of foreign DNA insertion, pTG2Ol becomes more unstable than pBR322, when assayed in the same conditions and strains of E . coli [3, 41. Recently several authors [3, 51 showed, that the immobilization of E. coEi cells, carrying pTG2Ol plasmid, can improve the plasmid stability and the expression of cloned genes in relation to free cell cultures. This phenomenoh shows good perspectives on its practical use but we know little about the mechanism that determines the different plasmid stability kinetics between free and immobilized cells of E. coli. On the other hand, the culture of immobilized cells in presence of pure oxygen has been assayed by several authors to ameliorate the cell growth in support of immobilization [6]. Consequently we are interested in knowing the kinetic behaviour of pTG201 unstability in free cells cultures in presence of different oxygen tensions.

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New method for the characterization of the microbial growth in carrageenan gel

Marín-Iniesta¹

1989

Acta Biotechnologica

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A method for the analysis of distributed growth of E. coli in k-carrageenan gel is described. The method iises optical and electron microscopy to determine morphometric data of cell microcolonies in the gel, such as average microcolony volume, distance of microcolonies to gel surface and cell density in the microcolonies. Logarithmic equations describing the distribution of authentic values of volunie occupied by cells in gels at different times of incubation mere determined. With these equations it is possible to predict the quantitative distribution of cells in the gel and to define some parameters. These parameters can characterize the growth behaviour of the microbial strains in any particular culture condition and can be useful in the future search to improve the industrial applications of immobilized cells.

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Immobilized Bacteria and Plasmid Stability

Cited by 11 publications

References 35 publications

Investigation of production of dextran and dextransucrase by Leuconostoc mesenteroides immobilized within porous stainless steel

Investigation of production of dextran and dextransucrase by Leuconostoc mesenteroides immobilized within porous stainless steel

Kinetic study of pTG201 plasmid stability in Escherichia coli

New method for the characterization of the microbial growth in carrageenan gel

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