TABLE 2.
Stimulation of growth of V. vulnificus strains by various iron sources and producer strains
| Producer strain or iron compound (concn) | Diam of zone of growth (mm) of indicator straina
|
||
|---|---|---|---|
| MO6-24 (wild type) | CML49 | CML49 (pCML42) | |
| Hemoglobin (10 μM) | 15 | 0 | 17 |
| Hemin (20 μM) | 15 | 0 | 16 |
| Transferrin (2.6 mM) | 15 | 12 | 14 |
| FeSO4 (10 mM) | 19 | 15 | 17 |
| Vulnibactin (2 mM) | 20 | 18 | 19 |
| MO6-24 | 14 | 13 | 17 |
| CML49 | 14 | 13 | 16 |
Cultures were seeded into LB agar containing 75 μg of EDDA per ml, and 5 μl of various iron-containing compounds or overnight growth of a bacterial strain was spotted onto the medium or onto sterile disks placed on the medium. Strains MO6-24 and CML49 were used as producer strains to detect any alteration in the ability to produce siderophores (e.g., vulnibactin) and the ability for the indicator strain to use siderophores as an iron source. The zones of growth around the spots or the disks were measured after 18 to 24 h. Diameter measurements include the size of the disks or spots except in instances of no growth around disks. The measurements represent the average of three experiments.