Although a vast amount of biochemical and physiological research has been done on the non-pathogenic fungi, comparatively, little has been done on the metabolic products of the fungi pathogenic to the higher forms of life, Bocobo (1), Nickerson (2, 3). Among the pathogenic fungi is Trichophyton rubrum, one of the dermatophytes. An outstanding characteristic of this group of microorganisms is their pigmentation, the coloring matters being found on the undersurface of the colony. Under controlled

more »

... conditions, the shade of pigmentation is believed to be fairly characteristic of many species and, therefore, the coloration is used as one of the criteria in classifying these fungi. The information available in the literature concerning the pigments of the dermatophytes is most meager and entirely descriptive. Sabouraud (4) quotes Truffi, who stated that the pigments of the Dermatophytes are acids, since he claimed that they are precipitated by bases. Tate (5) found that the pigments of T. rubrum and T. mentagrophytes are red to reddish-brown in color, easily soluble in dilute acids and acidified alcohol, and that they function as acid-base indicators, being yellow in an acid medium and red in an alkaline medium. He also claimed that an alkaline solution of the pigments could be reduced with sodium dithionite and reoxiclized by contact with air. Both the pH and oxidation-reduction effects could be reversed many times. In addition, he stated that the pigments are heat stable. Thompson (6) confirmed the results of Tate with T. gypseum and T. rubrum and extended these observations by finding that these pigments in solution turn a bluish-lavender at a pH above 9. He reported that such a solution, on standing, turned yellow but the lavender color could be restored by oxygen but not by nitrogen, hydrogen sulfide, or carbon dioxide. Tate (5) and also Georg and Maecheling (7) claimed that the pigments might be anthracene compounds. This statement is completely unsupported by published experimental evidence. Pinetti (8) has recently achieved a partial separation of the pigments in T. violaceum by means of chromatography on aluminum oxide, but none of the fractions were reported to be in crystalline form. Paldrok (9) , citing the work of Georg and Maechling, and of Nickerson, stated: "The causes of quantitative variation in pigment production in the Dermatophytes have not been elucidated as the pigment itself may be regarded as a single chemical substance and the changes in shade seem to depend solely on the pH and the reduction-oxidation potential of the cultures". A careful and exhaustive search of the literature failed to reveal any evidence whatsoever in * From the Graduate School of St. John's University, Brooklyn 6, N. Y. Abstracted in part from the Dissertations of Paul J. O'Brien, F. Louis Schmitt, and Arthur Sohier, submitted in partial fulfillment of the requirements for the M.S. degree.