Physicochemical characterization of the microbial Fe2 + chelator proferrorosamine from Pseudomonas roseus fluorescens

M. Vande Woestyne. B. Bruyneel and w. Verstraete. 1992. The microbial chelating compound proferrorosamine A, produced by Pseudomonas roseus fluorescens, formed a complex with Fe2 + of which the apparent stability constant was found to be 1023. The following order of increasing stability constants of metal complexes with proferrorosamine was established as: Ba2+, Ca2 +, Mg2+, Mn2+ < Hg2+ < Zn2+ < Pb2+ < Co2+ < Cu2 +∼ Fe2 + < Ni2+. Only Ni2 +-proferrorosamine had a stability constant which was established as: Ba2+, Ca2+, Mg2+, Mn2+ < Hg2+ < Zn2+ < Pb2 + < Co2 + < Cu2 +∼ Fe2 + < Ni2 +. Only Ni2+-proferrorosamine had a stability constant which was ca 32 times higher than Fe2 +-proferrorosamine. Because of the production of proferrorosamine the growth of Ps. roseus juorescens was not inhibited in iron limiting media by the addition of 0.15 mmol/l of the weaker chemical Fe2 + chelator 2,2′-dipyridyl. This contrasted with the proferrorosamine-negative mutant K2 and Ps. stutzeri, which only produces Fe3+-chelating siderophores. Furthermore, it was found that proferrorosamine was able to dissolve Fe2+ from stainless steel. These results show that proferrorosamine is a strong and selective Fe2+ chelator which could be used as an alternative for the toxic 2,2′-dipyridyl to control lactic acid fermentations.