Immobilized and free cell continuous cultures of a recombinant E. coli producing catechol 2,3-dioxygenase in a two-stage chemostat: improvement of plasmid stability.
The immobilization of recombinant strains of E. coli W3110/pTG205 in K-carrageenan gel beads improves the plasmid stability during continuous cultures in the absence of selection pressure. Since, xyl E gene (which encodes catechol 2,3-dioxygenase from Pseudomonas putida) transcription is controlled by the trp promoter, the effects of tryptophan (repressor) and 3 beta-indolyl acrylic acid (derepressor) on pTG 205 stability and enzyme production have been studied in both free and immobilized cell cultures. A two-stage continuous culture system running for 150 h is described. In the first stage an immobilized culture is performed in the presence of tryptophan with a significant plasmid stability. The cells released from the gel beads are continuously transferred in the second stage reactor where expression is induced by 3 beta-indolyl acrylic acid. In these conditions an efficient production of catechol 2,3-dioxygenase is observed.
Laboratoire de Technologie Enzymatique, Université de Technologie de Compiègne, France.
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F
Berry
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S
Sayadi
M
M
Nasri
D
D
Thomas
J N
JN
Barbotin
D001709:Biotechnology / Q000379:methods; D050557:Catechol 2,3-Dioxygenase; D003001:Cloning, Molecular / Q000379:methods; D049308:Dioxygenases; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D010105:Oxygenases / Q000096:biosynthesis*; D010957:Plasmids / Q000187:drug effects / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011549:Pseudomonas / Q000201:enzymology / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis
D011994:Recombinant Proteins; D010105:Oxygenases; D049308:Dioxygenases; D050557:Catechol 2,3-Dioxygenase