Amino acid composition of fungi during development in submerged culture

Abstract

Determination of free amino acids and of bulk-protein composition in Penicillium griseofulvum were made at different stages of shaken culture on a glucose-ammonia medium. Changes in size and composition of the amino-acid pool occurred during conidial germination, the exponential growth phase, and the subsequent phase of N starvation. The bulk-protein composition was stable throughout culture. A hot-water-extractable fraction yielding amino acids on hydrolysis ("peptide" fraction), of which glutathione was a major component, was present in mycelium and conidia. The non-glutathione part of this fraction increased during N starvation. Combined amino acids also accumulated in the culture medium after exhaustion of the inorganic N supply. The composition of the amino-acid pool of conidia, particularly the glutamic acid and gamma-aminobutyric-acid contents, varied between samples with different histories. The pool was smaller than in mycelium and contained consistently a higher proportion of glutamine and a lower proportion of other components, especially alanine. No differences in amino-acid composition were detected between vegetative and sporogenous cultures of P. griseofulvum. Five other molds had amino-acid pools that were generally similar to those of P. griseofulvum at comparable stages of development.