Fur mutants FPA12 and FF13 of strains Pseudomonas aeruginosa PAO1 and Fe10, respectively, were prepared and their production of pyoverdin evaluated. The strains were cultivated in stirred bioreactor in iron-deficient and iron-supplemented medium containing Casamino acids (CA) or succinate as a source of carbon and energy. When the pyoverdin production rate reached its maximum, the demand of iron-depleted cultures for O-2 was decreased. Mutant FF13 overproduced pyoverdin in both iron-depleted (862 mg l(-1)) and iron-supplemented (428 mg l(-1)) CA medium and could also be used to produce pyoverdin when grown in a conventional stirred tank fermenter.