TABLE 1.
Bacterial strains and plasmids
| Strain or plasmid | Relevant characteristic(s)a | Source or reference |
|---|---|---|
| L. lactis subsp. lactis LM0230 | Lac− Prt− plasmid-free derivative of c2 | 9 |
| S. thermophilus | ||
| ST3-1 | Plasmid-free strain | 15 |
| ST4-1 | Industrial strain | DSM Food Specialties |
| E. coli JM109 | Transformation host | 14 |
| Plasmids | ||
| pGKV210 | 4.4 kb; Cmr Emr | 11 |
| pND312 | 7.0 kb; Cdr; 1.8-kb AccI fragment deleted from a native plasmid of L. lactis | 7 |
| pND913 | 6.4 kb; Ampr Emr Cdr; 2.9-kb fragment encoding Cdr from pND312 into pND913 | 15 |
| pND918 | 9.3 kb; Ampr Emr Cdr; 2.9-kb fragment from pND312 into pND913 | This study |
| pND919 | 5.0 kb; Cdr; 4.1-kb KpnI non-food-grade fragment deleted from pND918 | This study |
a
Ampr, ampicillin resistant (or Carbr); Cmr, chloramphenicol resistant; Lac, lactose fermenting; Prt, proteinase producing.