Classification of some Gymnoascaceae by pyrolysis-gas-liquid chromatography using added marker compounds.

Methyl esters of fatty acids were added to samples before pyrolysis to superimpose peaks of known retention time on the pyrochromatograms. These peaks were useful in calibrating the retention time scales so that peaks on different chromatograms could be appropriately homologized. The study included 3 species of Nannizzia, 3 strains of Trichophyton rubrum and 1 strain each of Gymnoascus uncinatus, G. reesii, Arachniotus hyalinosporus, Chrysosporium pannorum and Gliocladium viride. Pyrograms of the 3 T. rubrum strains were not as similar to each other as the pyrograms of some of the supposedly distantly related species. Unless our identification of 1 or more of the T. rubrum strains is incorrect, these results cast doubt on the usefulness of pyrochromatograms as indicators of genetic similarity.