A STUDY OF THE NUTRITIONAL-REQUIREMENTS OF A SELECTED HAEMOPHILUS-DUCREYI STRAIN BY IMPEDANCE AND CONVENTIONAL METHODS

The growth and nutritional requirements of Haemophilus ducreyi (CIP 54 2T) were determined in liquid media by impedance technology. We found that H. ducreyi grew in a liquid mixture of Proteose Peptone No. 3, he min, L-serine, glucose, L-glutamine, and inorganic salts. The peptone in the medium was essential for H. ducreyi growth, and the growth fact or (or factors) in the peptone was stable to autoclaving (15 min, 121- degrees-C) and could not be extracted with organic solvents (2:1 chlor oform/methanol) from either acidic (1 N CH3COOH), neutral (pH 7.1), or basic (1 N NaOH) solutions. Hemin was also an essential component for the growth of H. ducreyi, but a much lower concentration of hemin (5. 0 mug/ml) was required than has been previously reported in the litera ture (25 mug/ml). Using impedance technology to measure H. ducreyi dou bling times, we showed that bovine albumin enhances H. ducreyi growth.