Amino acid- or protein-dependent growth of Trichophyton mentagrophytes andTrichophyton rubrum

Culture conditions were examined for Trichophyton mentagrophytes and Tricho phyton rubrum, which are major pathogens involved in dermatophytosis. They grew well in Sabouraud's dextrose broth or RPMI 1640. Growth in phosphate-b uffered yeast nitrogen base supplemented with glucose was very slow, althou gh growth improved significantly with the addition of amino acids or protei ns to the medium. The fungi could also grow using human nail fragments as t he only source of nutrition. Examination of proteases by substrate gel elec trophoresis indicated that distinct sets of proteases are secreted from the dermatophytes in two different media, Sabouraud's dextrose broth and nail fragments. A protease inhibitor, phenylmethanesulfonyl fluoride, inhibited the growth of the fungi on nail fragments, but it did not inhibit their gro wth in Sabouraud's dextrose broth. (C) 2000 Federation of European Microbio logical Societies. Published by Elsevier Science B.V. All rights reserved.