Cultivation of fungi in synthetic and semi-synthetic liquid medium. I. Growth characteristics of the fungi and biochemical properties of the isolated antigenic material.

Four allergologically important fungi, viz. Aspergillus fumigatus, Alternaria Penicillium notatum, and Cladosporium herbarum, were cultured in a pure synthetic medium and the patterns of growth as characterized by the pH, protein and carbohydrate concentration of the culture fluid, were studied. A fumigatus and P. notatum showed a similar growth pattern, characterized by a rapid decrease in the pH of the culture medium (pH 7.4----4.0), while proteins were slowly released and saccharose poorly consumed. In contrast, A. alternata and C. herbarum demonstrated a different pattern of growth, in which the pH of the culture hardly changed during incubation. Enrichment of the synthetic medium with yeast extract greatly improved the growth of all four fungi, as was confirmed by the enhanced yield of antigenic material and strongly increased consumption of saccharose. The yeast extract especially changed the growth pattern of A. fumigatus and P. notatum, which now is characterized by three phases. Phase I: fall in pH of the growth medium and excretion of proteins; phase II: increase in pH and fall in protein concentration; phase III: stabilization of pH at alkaline values and renewed excretions of proteins. It is concluded that during cultivation of the fungi, the metabolic state of the culture changes, influencing the antigenic composition of the extracts obtained after different periods of cultivation.