Gx Biosystems A/s

A/s Alfred Benzon

Benzon Pharma, A/s

Soren Molin

Michael Givskov

Leo Eberl

Asim K Bej

Claus Sternberg Kristensen

Erik Riise

Jens E Larsen

Janice A Light

The survival of cells is limited by introducing into the cells a regulatably expressible gene whose expression results in the formation of a cytoplasmatically active hydrolytic enzyme. Populations of cells containing, in addition to such a regulatably expressible gene, a DNA coding for an immunologically active, pesticidally active or environmental pollutant-degrading gene product, may be useful in immunologically active compositions, pesticidally active compositions and environmental pollutant-degrading compositions, respectively.

Method of limiting the survival of genetically engineered microorganisms

The survival of cells is limited by introducing into the cells a regulatably expressible gene whose expression results in the formation of a cytoplasmatically active hydrolytic enzyme. Populations of cells containing, in addition to such a regulatably expressible gene, a DNA coding for a pesticidally active or environmental pollutant-degrading gene product, may be useful in pesticidally active compositions and environmental pollutant-degrading compositions, respectively.

Extracellular Serratia spp. enzymes have been found to be excreted by another gram-negative organism harbouring a plasmid carrying DNA from Serratia spp. encoding the enzymes. This organism, e.g. E. coli, is therefore employed to produce the enzymes, specific examples of Serratia spp. enzymes produced are a nuclease, a lipase and a phosopholipase. The nuclease may be employed to remove nucleic acids from a biological material.

Production in Escherichia coli of extracellular Serratia spp. hydrolases

Plasmids useful as cloning vectors carrying an inserted regulatable promoter, transcription from the promoter regulating plasmid replication. Increased transcription leads to a substantially increased or uncontrolled plasmid copy number when host microorganisms containing the plasmid are cultivated under conditions securing such increased transcription. The regulatable promoter is preferably .lambda. P.sub.R, the activity of which is controlled by a temperature-sensitive .lambda. cl repressor. To obtain gene products of the plasmids, host microorganisms to which such plasmids have been transformed are desirably cultivated at about 30.degree. C. to secure a constant, low plasmid copy number during the seeding and multiplication stages of the microorganisms, after which the temperature is preferably shifted to about 36.degree.-42.degree. C. to obtain an uncontrolled plasmid copy number and an amplified amount of gene product.

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Holte, Denmark

Soren Molin