IRON ACQUISITION FROM TRANSFERRIN AND LACTOFERRIN BY PSEUDOMONAS-AERUGINOSA PYOVERDIN

Growth of Pseudomonas aeruginosa ATCC 15692 was promoted when the stra in was cultured in an iron-depleted succinate medium, supplemented wit h transferrin at 30%, 60% and 100% and lactoferrin at 60% and 100% iro n-saturation. No significant differences between cell growth and pyove rdin production were observed when transferrin iron saturation was inc reased from 30% to 100%; however, cell growth and pyoverdin production were strongly dependent on lactoferrin iron saturation. Lower lactofe rrin iron saturation (< 30%) resulted in more pyoverdin production and reduced cell growth. Incubation of pyoverdin (1.0 mu M) with 10.0 mu M transferrin (30%, 60% and 100% iron-saturated) or lactoferrin (60% a nd 100% iron-saturated) led to quenching of pyoverdin fluorescence. Al so, 24 h incubation of pyoverdin (20.0 mu M) with these two proteins ( 20.0 mu M, 30%, 60% and 100% iron-saturated transferrin and 60% and 10 0% iron-saturated lactoferrin) at 25 degrees C resulted in increased a bsorbance at 460 nm. both the fluorescence quenching and absorbance in creases were iron-saturation-dependent. Taken together, these results support the conclusion that at physiological ph, P. aeruginosa pyoverd in can acquire iron from partially iron-saturated transferrin or lacto ferrin.