Isolation of Pseudomonas fluorescens producing phenazine derivatives exclusively under strains conditions of iron deficiency.

We succeeded in isolating biotypes of Pseudomonas fluorescens forming phenazine derivatives exclusively under conditions iron deficiency. A culture medium containing traces of beryllium with glucose as the only carbon source allowed these microorganisms to grow under production of a brilliant red colour. Without beryllium the colonies were brown in colour. Spectroscopic investigations showed the red pigment to be a mixture of di- and trihydroxyphenazine carboxylic acid. UV/VIS measurements of the culture medium indicated the additional presence of ironcomplexing proferro-rosamines.