Pityrosporum ovale —A Lipophilic Fungus. Thiamin and Oxaloacetic Acid as Growth Factors *

Abstract

Summary and Conclusions

Thiamin when added to a basal medium containing KH₂PO₄, MgSO₄ and with asparagin or NH₄Cl causes an increase in the growth of Pityrosporum ovale. With asparagin the increase is much greater than with NH₄Cl. However, if ethyl oxalacetate replaces the thiamin, growth in the NH₄Cl medium is just about equal to that in the asparagin medium. The addition of thiamin to the medium containing oxalacetate does not cause any further increase in growth. It would seem then that NH₄Cl and ethyl oxalacetate can be substituted for asparagin and thiamin in the cultivation of Pityrosporum ovale. It appears that if a suitable keto acid is supplied neither thiamin nor an amino acid is necessary. On the other hand, the asparagin may furnish both the carbon and nitrogen source needed by the organism, yielding ammonia and a carbon skeleton, probably oxalacetate. Thiamin increases growth when added to the asparagin by hastening the production of the carbon skeleton in some way. When this carbon skeleton is supplied as oxalacetate, thiamin is no longer necessary.