TABLE 5.
Suppression of siderophore overproduction under high-iron growth conditions by complementation of mutant alleles of the irp6 operon in C. diphtheriaea
| Strain | Plasmid | Siderophore level (U/ml) in:
|
|
|---|---|---|---|
| Low iron | High iron | ||
| C7(β) | pCM2.6 | 451 ± 30 | 26 ± 3 |
| pCM6ABC | 396 ± 3 | 26 ± 1 | |
| HC1 | pCM2.6 | 514 ± 12 | 386 ± 40 |
| pCM6ABC | 452 ± 19 | 53 ± 3 | |
| pCM6AB | 372 ± 35 | 43 ± 0 | |
| pCM6A | 332 ± 29 | 60 ± 8 | |
| HC3 | pCM2.6 | 576 ± 54 | 187 ± 10 |
| pCM6ABC | 585 ± 54 | 236 ± 58 | |
| HC4 | pCM2.6 | 499 ± 11 | 353 ± 109 |
| pCM6ABC | 594 ± 6 | 63 ± 10 | |
| pCM6AB | 411 ± 61 | 285 ± 18 | |
| pCM6A | 333 ± 26 | 460 ± 141 | |
| HC5 | pCM2.6 | 291 ± 10 | 194 ± 29 |
| pCM6ABC | 236 ± 35 | 44 ± 5 | |
| pCM6AB | 111 ± 14 | 3 ± 0 | |
| pCM6A | 109 ± 21 | 111 ± 8 | |
a
Supernatants from overnight cultures grown in modified PGT medium (mPGT) (low iron) or mPGT plus 10 μM FeCl3 (high iron) were used for siderophore assays. Values represent means ± standard deviations of assays performed on cultures grown in triplicate.