TABLE 1.
Bacterial strains and plasmids used in this study
| Strain or plasmid | Genotype or phenotypea | Source or reference |
|---|---|---|
| Lactobacillus delbrueckii subsp. lactis | ||
| LL44 (NCC936) | Inducible lac operon | Our collection |
| LL44/6 (NCC2727) | ΔlacR, constitutive lac operon | NCC936; this work |
| N62 (NCC181) | Inducible lac operon | NCDO270 |
| N141 (NCC2506) | Inducible lac operon | Our collection |
| LB68 (NCC653) | Inducible lac operon | ATCC 21815 |
| Lactobacillus delbrueckii subsp. bulgaricus | ||
| N299 (NCC2515) | Constitutive lac operon | ATCC 11842T |
| YL5 (NCC408) | Constitutive lac operon | Our collection |
| Lactococcus lactis | ||
| MG1363 | Plasmid-free derivative of NCDO 712, lac mutant | 3 |
| Plasmids | ||
| pNZ272 | Camr, promoterless gusA gene, shuttle E. coli; gram positive | 20 |
| pNZ273 | Camr, pNZ272 derivative | 20 |
| pLL110 | pNZ272 with LL44 lac promoter | This work |
| pLL112 | pNZ272 with LL44 lac promoter, LL44 lacR gene | This work |
| pLL113 | pNZ273 with N299 lac promoter | This work |
| pLL116 | pNZ273 with N299 lac promoter, LL44 lacR gene | This work |
a
Camr, chloramphenicol resistant.