Construction of a food-grade host/vector system for Lactococcus lactis based on the lactose operon |
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Authors: | Caroline A. Maccormick Hugh G. Griffin Michael J. Gasson |
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Affiliation: | Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, UK |
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Abstract: | Abstract A plasmid-based food-grade vector system was developed for Lactococcus lactis by exploiting the genes for lactose metabolism. L. lactis MGS267 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. |
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Keywords: | Lactococcus lactis Lactose operon Food-grade vector lacF deletion lacF complementation |
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