GROWTH AND CYTOCHEMICAL DIFFERENTIATION OF MOLD COLONIES

Abstract

The colonies of Aspergillus niger and Penicillium urticae were grown on cellophane membranes placed on agar media, and paraffin sections of the isolated colonies were examined comparatively by cytochemical methods. Hyphal cells showing high degree of basophilia were located mainly in the growing outer region, especially in the surface layer, of the colonies. The basophilic substances present in the surface layer of the outer region seemed to move into fruiting bodies that reproduce conidia. Fruiting bodies located in the outer region were the most basophilic of all parts of the colonies, whereas those in the central region were less or not basophilic; most of the basophilic substances might have been transferred into the condia from these bodies. A metachromatic substance, which is considered to be polyphosphate, was highly concentrated in the fruiting bodies in granular forms. This substance was also transferred into the conidia as the colonies developed. In general, no essential difference was observed between the colonies of the two fungi tested.