X-RAY-MICROANALYSIS OF BLACK PIEDRA

The elements present in the fungal structures produced by Piedraia hor tae in vivo and in vitro have been investigated using electron microsc opy X-ray microanalysis. Phosphorus, sulphur and calcium were detected in the nodules which developed on hair and on colonies on culture. Th ese elements belong to the extracellular material that compacts the ps eudoparenchymatous organization of the fungus. They may be present due to the capacity of melanin-like pigments to sequester ions and/or the y may form part of the sulphates and phosphates of the polyanionic muc opolysaccharides that constitute the extracellular material. Environme ntal contaminants such as aluminium, silicon and iron were detected ex clusively on the surface of the nodule. They were deposited or linked to the residual molecules produced during the breakdown of the cuticul ar keratin. The advantages of these techniques for elucidating the che mical nature of fungal structures are discussed.