Lactococcus lactis Constitutive Expression System Vector

The Constitutive Gene Expression System for Lactococcus lactis and other lactic acid bacteria, developed at NIZO Food Research, NL, is a food-grade protein expression system. This system is advantageous in that it does not contain endotoxins, inclusion bodies, spores or extracellular proteases, and can be used for bacteria other than L. lactis. With this system, fermentation, scale-up and downstream processing are simple.

The L. lactis expression vectors are all based on the pSH71 rolling circle replicon. Vectors for cloning and constitutive expression are offered:

• pNZ124 (ELV01100) - General broad-host-range cloning vector with multiple cloning site for L. lactis and other lactic acid bacteria; chloramphenicol selection.

• pNZ2103 (ELV01200) - Broad-host-range vector for constitutive gene expression under control of the lacA promoter; for transcriptional fusion; chloramphenicol selection.

• pNZ2105 (ELV01150) - General food grade cloning vector with multiple cloning site for L. lactis NZ3000; lacf-based selection.

• pNZ2122 (ELV01300) - Food grade vector for constitutive gene expression under control of the lacA promoter for L. lactis NZ3000; for transcriptional fusions; lacf-based selection.

• pNZ2123 (ELV01350) - Food grade vector; identical to pNZ2122 but with inverted multiple cloning site; lacf-based selection.

• pNZ2125 (ELV01400) - Food grade cloning vector with multiple cloning site appropriate for gene expression into L. lactis strain NZ1330; alr-based selection.

• pNZ7021 (ELV01250) - Broad-host-range vector for constitutive gene expression under control of a strong promoter PpepN; Chloramphenicol selection. This vector is designed for translational fusions. It contains the pepN ribosome binding site (RBS) and a start codon (ATG) followed by an SphI site which is essential for the cloning of a target gene without its own ribosome binding site and start codon.

• pNZ7025 (ELV01450) - Food grade vector for constitutive gene expression under control of the pepn promoter; alr-based selection. This vector is also designed for translation fusions as described above for the plasmid pNZ7021.