Development and application of a bioassay to study the effects of nutrients, pH, and active substances on Sordaria macrospora fruiting

Abstract

The perithecial development of Sordaria macrospora (Auersw.) is prevented by ammonium salts as nitrogen source, but only below a critical initial pH in the culture medium. Around this point, a very small variation in the initial pH can induce a morpho-genetic change. Within the inhibition range, supplementation of the culture medium with aqueous cell-free extracts from the fruiting mycelia or fruiting bodies of some fungi overcomes the ammonium inhibition. This phenomenon was used to develop a biological test which could be used to isolate, for the determination of their chemical structure, active fungal substances. The precise physiological conditions required to obtain good reproducibility and reliability with this bioassay have been established, which allows the important effects of nutrients and pH on S. macrospora fruiting to be determined. An application is described with the isolation and characterization of hercynine, an active substance purified from Agaricus bisporus fruiting bodies. Its activity is compared with that of other basic substances.