The Relation of Nutrition to the Growth and Morphology of Trichophyton Violaceum. I. The Vitamin and Amino Acid Requirements of T. Violaceum

SUMMARY

1.	T. violaceum grows slowly and poorly on Sabouraud's dextrose agar. The colonies are usually small, and glabrous, and consist of a mass of poorly developed mycelium and chlamydospores.
2.	Of eleven strains studied on synthetic, chemically defined medium, ten showed a partial requirement for thiamine. The minimum effective quantity was 0.002 μg. in 5 ml. NH4NO3 broth.
3.	Thiamine could be replaced for these strains by an equimolar amount of pyrimidine (2-ethoxy-methyl-6 amino pyrimidine).
4.	Oxalacetate was found to substitute partially for thiamine under the conditions studied.
5.	Growth of the thiamine-deficient strains was somewhat stimulated by comparatively large doses of para-aminobenzoic acid.
6.	In the presence of maximum effective dosages of thiamine, further stimulation of growth was observed with the addition of casein or other peptones.
7.	One strain (No. 365) was morphologically and physiologically distinct from the others in that it grew rapidly on Sabouraud's dextrose agar, producing a white, fluffy colony with large numbers of microconidia. It required the amino acid, l-histidine, for growth and was not stimulated by either thiamine or para-aminobenzoic acid.
8.	A single spore culture of strain No. 365 developed sectors which had morphological and physiological characters identical with those of ten other T. violaceum strains studied. Strain No. 365 is considered to be an unstable mutant form of T. violaceum.