Element localisation and distribution in the fungi Aureobasidium pullulans and Aspergillus niger, measured using the Oxford scanning proton microprobe.

The distribution and relative concentrations of essential elements were determined in germ tubes of Aureobasidium pullulans and hyphae of Aspergillus niger using the Oxford scanning proton microprobe. In both fungi, K, P and S were the major constituents, with Ca, Na and trace metals like Cu, Mn, Fe and Zn present at lower levels. In A. pullulans, elements were not distributed uniformly throughout the cells and, in general, the highest elemental concentrations occurred at the tip and in the older parts of the germ tube, particularly where there was yeast-like cell or branch development. In A. niger, elemental distribution was more uniform and there was a general gradient of increasing concentration away from the hyphal tip followed by a drop in levels in older regions. The scanning proton microprobe appears to have considerable potential for the investigation of fungal differentiation and morphogenesis.