Abstract
Although it is well known that Moraxella bovis produces a hemolytic substance, little work has been done to characterize this substance. This report describes the condition of production of the hemolytic substance and its properties examined with strains of M. bovis isolated from otorrhea of cases of chronic otitis media and ATCC 10900, a type strain of the species.
The growth of ATCC 10900 was enhanced by the addition of yeast extracts (0.5%) to heart infusion medium at pH 7.5, and a sufficient amount of hemolytic substance was produced in this medium. It is not likely that yeast extract directly accelerated the production of the hemolytic substance. Smooth colonies of M. bovis seemed to produce a higher level of the hemolytic substance than rough colonies. Trypsin, when added to the medium at the time of incubation, inhibited the production of the hemolytic substance. None of such other agents as Fe++, Mg++, oxidizing or reducing agents, surface active agents and lecithin did not affect its production.
The substance of all strains hemolysed horse and sheep red blood cells, however that of 80% of the strains hemolysed human red blood cells and 75% rabbit red blood cells. The production was markedly accelerated by keeping the culture for 24hr at 4C after incubation at 30C.
The hemolytic substance of M. bovis is an extracellular substance, stable to heat, soluble in water, and a ninhydrin-positive, basic substance of low molecular weight.
