Accessory Growth Factor Requirements of Some Members of the Pasteurella Group

Abstract

Most members of the Pasteurella group of bacteria develop satisfactorily in meat infusion-peptone media but fail to grow in simpler media made from hydrolyzed purified protein or in synthetic media. The substances in infusions of meat, other tissues or yeast which are needed for growth have not been previously identified. Accordingly we wish to report preliminary results of a study of the accessory growth factor requirements of some members of this group of organisms in which it will be shown that nicotinamide, pantothenic acid and, in some cases, the butyl factor for Clostridia are needed for prompt development.∗

Seventeen typical Pasteurella strains were used. These were stock laboratory cultures which had been secured from different sources. They were isolated originally from hemorrhagic septicemias in various species of animals. The results presented in this report apply only to the typical strains of animal origin and not to other species at times included in this genus.

The basal medium consisted of a 0.5% solution of hydrolyzed purified gelatin to which was added a supplement of 8 amino acids, 0.3% glucose, 0.5% NaCl, 0.2% K₂HPO₄, 0.005% MgSO₄ and 0.001% CaCl_2. To this was added 1 cc of Hoagland salt mixture per liter of medium. The amino acid supplement consisted of 20 mg each of valine, tyrosine, tryptophane, cystine, methionine and histidine and 15 mg each of serine and threonine per liter. The medium was adjusted to pH 7.0 with N NaOH solution and tubed in 5 cc quantities.

The accessory growth factors were sterilized by filtration and added aseptically to the basal medium. In the first tests a mixture of known substances was used on the assumption that perhaps some of them might be required by these organisms.