Table 2 Bacterial strains and plasmids utilized in this study

Strains

 E. coli DH5α

Cloning host; F-φ80lacZ△M15endA1 recA1 endA1 hsdR17 (rK-mK+) supE44 thi-1 gyrA 96 relA1 △(lacZYA-argF)U169 deoR λ-

[58]

 E. coli DH5α-up

Cm^r, Em^r, E. coli DH5α derivative containing the whole plasmid pNZ5319-up

This study

 E. coli DH5α-up-down

Cm^r, Em^r, E. coli DH5α derivative containing the whole plasmid pNZ5319-up-down

This study

 Micrococcus luteus NCIB 8166

Indicator strains for Nisin agar gel diffusion assay

[59]

 L. lactis NZ9000

MG1363 pepN::nisRK

[60]

 L. lactis N8

Wild-type (WT) Nisin Z producer

[27]

 L. lactis N8-up-down

Cm^r, Em^r, L. lactis N8 derivative containing the whole plasmid pNZ5319-up-down (single cross-over)

This study

 L. lactis N8-cat

Cm^r,L. lactis N8 derivative containing the a lox66-P32-cat-lox71 replacement of PRF (double cross-over)

This study

 L. lactis N8-1

Mutant. The PRF deletion from L. lactis N8

This study

 L. lactis N8-vector1

Cm^r, L. lactis N8 derivative containing pNZ8048

This study

 L. lactis N8-nisZ

Cm^r, L. lactis N8 derivative containing pNZ8048-nisZ

This study

 L. lactis N8-1-vector1

Cm^r, L. lactis N8-1 derivative containing pNZ8048

This study

 L. lactis N8-1-nisZ

Cm^r, L. lactis N8-1 derivative containing pNZ8048-nisZ

This study

 L. lactis N8-vector2

Em^r, L. lactis N8 derivative containing pLEB124

This study

 L. lactis N8-nisFEG

Em^r, L. lactis N8 derivative containing pLEB672

This study

 L. lactis N8-nisIFEG

Em^r, L. lactis N8 derivative containing pLEB124-nisIFEG

This study

 L. lactis N8-nisRKFEG

Em^r, L. lactis N8 derivative containing pLEB674

This study

 L. lactis N8-1-vector2

Em^r, L. lactis N8-1 derivative containing pLEB124

This study

 L. lactis N8-1-nisFEG

Em^r, L. lactis N8-1 derivative containing pLEB672

This study

 L. lactis N8-1-nisIFEG

Em^r, L. lactis N8-1 derivative containing pLEB124-nisIFEG

This study

 L. lactis N8-1-nisRKFEG

Em^r, L. lactis N8-1 derivative containing pLEB674

This study

Plasmids

 pNZ5319

Cm^r, Em^r, used as knock-out vector

[31]

 pNZ5319-up

Cm^r, Em^r, upstream homology arm amplified from L. lactis N8 genome cloned into pNZ5319

This study

 pNZ5319-up-down

Cm^r, Em^r, upstream and downstream homology arm amplified from L. lactis N8 genome cloned into pNZ5319

This study

 pNZTS-Cre

Em^r, cre gene cloned at the EcoRI and HindIII sites (cat gene deletion vector)

[53]

 pNZ8048

Cm^r, pNZ8048 derivative containing the promoter P8

[61]

 pNZ8048-nisZ

Cm^r, pNZ8048 derivative containing the promoter P8/nisZ

[61]

 pLEB124

Em^r, L. lactis secretion vector harboring lactococcal promoter P45

[27]

 pLEB672

Em^r, pLEB124 derivative containing the nisFEG gene

[62]

 pLEB124-nisIFEG

Em^r, pLEB124 derivative containing the nisIFEG gene

From Per Saris’ lab

 pLEB674

Em^r, pLEB124 derivative containing the nisRKFEG gene

[62]