TABLE 1.
Bacterial strains and plasmids
| Strain or plasmid | Relevant genotype or characteristicsa | Source or reference |
|---|---|---|
| Strains | ||
| Listeria monocytogenes | ||
| LO28 (serotype 1/2c) | betL+gbu+ | P. Cossart, Institut Pasteur |
| LO28ΔG, formerly GSOE | LO28 Δgbu | 31 |
| LO28ΔBG, formerly BGSOE | LO28 ΔbetL Δgbu, exhibits no detectable betaine uptake | 31 |
| LO28nΔBG | PnisA expression host (LO28ΔBG harboring pNZ9530) | This study |
| LO28nΔBG(pCPL17) | LO28nΔBG containing pCPL17 (betL under PnisA control) | This study |
| LO28nΔBG(pNZ8048) | LO28nΔBG containing the cloning vector pNZ8048 with no insert | This study |
| Lactococcus lactis NZ9700 | Nisin-producing transconjugant containing Tn5276 | 14 |
| Plasmids | ||
| pNZ8048 | Cmr, carries the nisin-inducible promoter PnisA | 6 |
| pNZ9530 | Eryr, nisRK cloned in pIL252, expression of nisRK driven by rep read-through, low copy number | 11 |
| pCPL17 | pNZ8048 plus a promoterless copy of betL | This study |
a
Cmr, chloramphenicol resistant; Eryr, erythromycin resistant.