Identification of the siderophores from Vibrio hollisae and Vibrio mimicus as aerobactin.

Hydroxamate siderophores were purified from low-iron cultures of Vibrio hollisae ATCC 33564 and Vibrio mimicus ATCC 33653. By a combination of 1H and 13C NMR spectroscopy, fast atom bombardment mass spectrometry, and compositional analysis, both of the siderophores were identified as aerobactin, a citrate-based dihydroxamate siderophore, which is highly prevalent in species of the family Enterobacteriaceae. Four other clinical strains belonging to these species also produced aerobactin. In response to iron limitation, all strains expressed two high molecular mass outer membrane proteins. The protein with an apparent molecular mass of 77 kDa, which was common to all strains examined, may be the ferric aerobactin receptor.