TABLE 2.
Antibiotic productivity of bacterial streptomycin-resistant mutants
| Microorganism | MIC (μg/ml) | Concn of streptomycin used for selecting str mutants (μg/ml) | Antibiotic (production [μg/ml]) in parental (wild-type) strain | Frequency (%) of str mutants producing increased antibioticc | Highest productivity detected (μg/ml) |
|---|---|---|---|---|---|
| S. chattanoogensis | 1 | 30 | Fredericamycin (10) | 46 (46/100) | 260 |
| S. antibioticus | 1 | 5 | Actinomycin (12) | 4 (2/50) | 63 |
| S. lavendulae | 1 | 5 | Formycin (25) | 3 (2/60) | 130 |
| P. pyrrocinia | 100 | 300 | Pyrrolnitrin (1.5) | 30 (30/100) | 15 |
| B. cereus | 1 | 3 | FR900493 (76) | 7 (9/70) | 550 |
| B. subtilisa | 1 | 5 | B. subtilis antibiotic (8)b | 3 (7/240) | 380b |
| 1 | 400 | B. subtilis antibiotic (8)b | 19 (37/194) | 80b |
a
Strain 168 was used.
b
Expressed in units per milliliter.
c
Mutants producing more than fivefold more antibiotic than the wild type. Numbers in parentheses are number of mutants producing increased antibiotic/number of mutants tested.