TABLE 3.
Transformation efficiency
| Strain | AdoCbla | Transformation efficiency (CFU/μg) with plasmidb: |
||
|---|---|---|---|---|
| pUC27H12 | pUC-Vmini | pUC-TT8 | ||
| WT | − | 1.2 × 103 | 7.3 × 103 | |
| + | 3.3 × 103 | 6.8 × 103 | ||
| PFW I-RNR | − | 1.2 × 105 | 2.3 × 104 | 5.2 × 104 |
| + | 7.8 × 104 | 9.8 × 103 | 8.3 × 104 | |
| PFW | − | 2.0 × 100 | 1.0 × 100 | 6.0 × 100 |
| + | 7.5 × 104 | 4.4 × 104 | 5.4 × 104 | |
a
+, T. thermophilus was cultured in liquid medium with supplementation with 0.1 μg/ml AdoCbl, mixed with the plasmid DNA, and then spread on an AdoCbl-supplemented plate. −, AdoCbl was added to neither the liquid medium nor the plate.
b
The plasmid DNAs prepared from PFW I-RNR were used for transformation. When plasmids prepared from E. coli were used, their transformation efficiencies were approximately 100-fold lower than those with the plasmids from PFW I-RNR. This is probably because of the chromosome-encoded restriction enzyme TthHB27I, which constitutes the restriction-modification system in T. thermophilus HB27.