A rapid screening system for exogenous gene knock-in Lactococcus lactis and its construction method and application

Abstract

The invention provides a rapid screening system for Lactococcus lactis with knocked-in exogenous genes. The screening system comprises temperature-sensitive plasmids and the Lactococcus lactis, wherein the temperature-sensitive plasmids contain his gene segments and temperature-sensitive replicon-erythromycin resistance gene (Ts-Emr) segments; chromosomes of the Lactococcus lactis contain lacZ gene expression segments. lacZ genes of the Lactococcus lactis cannot be expressed when the exogenous genes are knocked in successfully, so that white colonies are shown on a solid medium containing X-Gal, otherwise, blue colonies are shown, the change from the blue colonies to the white colonies can be directly observed on the solid medium, the screening workload can be greatly reduced, and screening time can be greatly shortened.

Description

technical field

[0001] The invention belongs to biological technology, specifically a new method for cloning an exogenous gene into the chromosome of Lactococcus lactis (Lactococcuslactis, L. More convenient and faster. Background technique

[0002] Lactococcus lactis (L.Lactis) is a non-invasive, non-pathogenic, food-safe, Gram-positive coccus traditionally used in the production of a variety of foods (e.g. cheese, butter, etc.) . Due to its important application value, Lactococcus lactis has been widely and deeply studied since the 1980s, and its biochemical, immune and genetic backgrounds have been studied clearly. Due to its good safety, Lactococcus lactis is widely used to express various foreign proteins, including various enzymes, therapeutic protein products and vaccine components, and is used in the fields of food industry, biopharmaceuticals and vaccine development, and has important economic value. Among them, L. lactis subsp. cremoris MG1363 and NZ9000 are mo...

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