Table 1.
Bacterial strains and plasmids used in this work
| Strain or plasmid | Descriptiona | Reference |
|---|---|---|
| L. lactis | ||
| MG1363 | Plasmid-free derivative of L. lactis NCDO712 | 16 |
| MG1614 | Strr Rifr derivative of L. lactis MG1363, Lcn972s | 16 |
| D1 | MG1614, highly Lcn972-resistant mutant | 34 |
| D1-20 | MG1614, low Lcn972 resistance mutant | 34 |
| NZ9000 | MG1363, pepN::nisRK; host for nisin-inducible gene expression | 12 |
| IL1403 | Plasmid free, complete ECF sigX gene | 2 |
| E. coli DH10B | Plasmid free, cloning host | Invitrogen |
| Plasmids | ||
| pCR2.1 | Cloning of PCR products, Apr | Invitrogen |
| pNZ8020 | Nisin-inducible promoter PnisA, Cmr | 12 |
| pPTPL | lacZ reporter plasmid, Tetr | 8 |
| pBL51 | pNZ8020::llmg2447 | This work |
| pBL51Cla | pBL51ΔClaI site, frameshift in llmg2447 | This work |
| pBL56 | pCR2.1::wild-type llmg2447 promoter (P2447) | This work |
| pBL57 | pCR2.1::hybrid IS981-llmg2447 promoter (PIS981::2447) | This work |
| pBL58 | pPTPL::wild-type llmg2447 promoter (P2447) | This work |
| pBL59 | pPTPL::hybrid IS981-llmg2447 promoter (PIS981::2447) | This work |
a
Str, streptomycin; Rif, rifampin; Em, erythromycin; Ap, ampicillin; Tet, tetracycline; superscript r, resistant; superscript s, susceptible.