EFFECT OF THE SIDEROPHORE ALCALIGIN-E ON THE BIOAVAILABILITY OF CD TOALCALIGENES-EUTROPHUS CH34

Alcaligin E, the siderophore of the heavy metal-resistant A. eutrophus strain CH34, was shown to interact with Cd and consequently affect it s bioavailability and toxicity. The addition of alcaligin E markedly s timulated the growth in the presence of Cd of an alcaligin E-deficient CH34 derivative, Using bioluminescence assays, this effect could be a ssigned to a decrease in bioavailability of Cd in the presence of alca ligin E, However, Cd-uptake studies showed no influence of alcaligin E on the cellular concentration of Cd, Furthermore, by scanning electro n microscopy, the morphology of precipitated Cd crystals was shown to be altered by alcaligin E, These data suggest that alcaligin E, beside s its function in iron supply to the cell, provides a protection again st heavy metal toxicity, A link between the A. eutrophus CH34 sideroph ore system and the czc-mediated Cd-efflux system is hypothesized.