The substratum photomorphogenesis — the increase of dry weight in light as compared with darkness — takes place only on the nutrient solution with yeast extract. On a synthetic medium with the phosphate level varying from 2.87 to 22.96 mM, the dry weight of mycelia is the same in light and in darkness. In a similar way the phosphorus content in the mycelia and the amount of this element taken up are not related to light conditions. The organism utilizes about 66% of the phosphate present in the nutrient solution.
Aspergillus giganteus mut. alba developing at high light intensities and glucose concentrations requires an increase in the level of nitrate in the synthetic nutrient medium to the level of the total amount of nitrogen in a medium enriched with yeast extract. The addition of ammonium ion to this medium increases distinctly the dry weight of mycelium grown in light when compared with mycelium developing in darkness.