title: Construction of a food-grade host/vector system for Lactococcus lactis based on the lactose operon.
abstract: A plasmid-based food-grade vector system was developed for Lactococcus lactis by exploiting the genes for lactose metabolism. L. lactis MG5267 is a plasmid-free strain containing the entire lactose operon as a chromosomal insertion. The lacF gene was deleted from this strain by a double cross-over homologous recombination event. The lacF-deficient strain produced a Lac- phenotype on indicator agar. A cloned copy of the lacF gene expressed on a plasmid was capable of complementing the lacF-deficient strain resulting in a Lac+ phenotype. This stably maintained system fits the requirements of a self-selecting vector system and has the potential to be exploited in the food industry.
authors.affiliation: Institute of Food Research, Colney, Norwich, UK.
authors.forename: C A
authors.initials: CA
authors.lastname: MacCormick
authors.forename: H G
authors.initials: HG
authors.lastname: Griffin
authors.forename: M J
authors.initials: MJ
authors.lastname: Gasson
mesh_terms: D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D005516:Food Microbiology; D017353:Gene Deletion; D005816:Genetic Complementation Test; D005822:Genetic Vectors; D007763:Lac Operon; D013294:Lactococcus lactis / Q000235:genetics*; D008969:Molecular Sequence Data; D010641:Phenotype; D010957:Plasmids / Q000235:genetics
chemical_list: D017931:DNA Primers