Pityrosporum Ovale

Using a medium suitable for continuous subculture ofPityrosporum ovale, the following observations have been made about this organism: The organism grows well in the pH range 7.5-8.3 and gradually acidifies the medium. Ammonium chloride and several amino acids stimulate growth but exogeneous vitamins seem relatively ineffective in promoting growth. Cysteine, as a sole source of amino nitrogen, does not support growth, possibly because of release of inhibitory sulfur-containing substances. This organism is incapable of solubilizing wool keratin. It can, however, utilize amino nitrogen-containing substances released from hard keratin by hydrolysis. Human serum temporarily inhibits the growth of P ovale. The inhibitory capacity is similar to that directed against Cryptococcus neoformans by human serum. P ovale elaborates substances that substantially inhibit the growth of all dermatophyte organisms so far investigated.