TABLE 1.
Bacterial strains and plasmids used in this study
Cmr, chloramphenicol resistance; Emr, erythromycin resistance; Tcr, tetracycline resistance. PnisA is a nisA promoter that is used for the nisin-controlled expression system (42). Pxyl is a xylose-inducible xylA promoter (43). JCM, Japan Collection of Microorganisms, Wako, Japan.
| Strain or plasmid | Description | Source or reference |
|---|---|---|
| Strains | ||
| Lactococcus lactis NZ9000 | MG1363 derivative; nisRK::pep | 38 |
| Staphylococcus carnosus TM300 | Plasmid-free | 39 |
| Staphylococcus aureus RN4220 | Cloning host | 40 |
| Lactobacillus sakei subsp. sakei JCM 1157T | Indicator strain of nukacin ISK-1 | JCM |
| Plasmids | ||
| pNZ8048 | Cmr, L. lactis expression vector with PnisA | 38 |
| pInuk | Emr, nukAMTFEGH | 18 |
| pInukdT | Emr, nukAMFEGH, disruption of nukT in pInuk | 18, 41 |
| pNZT | pNZ8048 derivative containing nukT downstream of PnisA | 18 |
| pNZT mutant | pNZT derivative; mutation introduced at indicated residue of NukT | This study |
| pTX15 | Tcr, staphylococcal expression vector with Pxyl | 39 |
| pTXnukT | pTX15 derivative containing nukT downstream of Pxyl | 15 |
| pTXnukT mutant | pTXnukT derivative; mutation introduced at indicated residue of NukT | This study |