TABLE 1.
Bacterial strains and plasmids used in this study
| Strain or plasmid | Relevant genotype and/or phenotype | Source or reference |
|---|---|---|
| Strains | ||
| Escherichia coli | ||
| TG1 | supE hsdΔ5 thi Δ(lacproAB) F′ [traD36proAB+lacIqlacZΔM15] | |
| TG1repA+ | TG1 derivative with repA gene integrated into the chromosome, allowing replication of L. lactis plasmids | P Renault, INRA, Jouy-en-Josas, France |
| M15(pREP4) | Derivative of E. coli K-12 containing pREP4 plasmid, ensuring the production of high levels of lac repressor protein; Kanr | QIAGEN |
| Lactococcus lactis | ||
| MG1363 | Plasmid free | 12 |
| MG1363acmAΔ1 | MG1363 derivative with a 701-bp deletion in acmA | 6 |
| MG1363acmB | MG1363 derivative with a 414-bp deletion in acmB and a Cmr cassette inserted; Cmr | 17 |
| MG1363acmAΔ1acmB | MG1363 derivative with deletions in both acmA and acmB; Cmr | 17 |
| MG1363yjgB | MG1363 derivative with a 333-bp deletion in yjgB | This study |
| TIL758 | MG1363 derivative, triple mutant acmA acmB yjgB; Cmr | This study |
| NZ9000 | MG1363, pepN::nisRK | 20 |
| htrA-NZ9000 | NZ9000 with htrA disrupted by single crossing-over recombination; Emr | 7 |
| TIL903 | htrA-NZ9000 containing pNZ8048 without insert | This study |
| TIL904 | htrA-NZ9000 containing pNZ8048::yjgB | This study |
| Plasmids | ||
| pQE60 | Expression vector for C-terminal six-His-tag fusion; Apr | QIAGEN |
| pG+host9 | Thermosensitive plasmid for gene replacement by double crossing-over integration; Eryr | 5 |
| pTIL752 | pG+host9 carrying a 1,602-bp fragment with a 333-bp deletion inside yjgB; Eryr | This study |
| pNZ8048 | Carries nisin-inducible nisA promoter for translational fusion; Cmr | 10 |