| Abstract: | Asparagine was a superior nitrogen source for clavine-alkaloid production in Claviceps purpurea. Its transport into the cell excedded the cell's biosynthetic need for this amino acid. Asparagine entered the cell without degradation. This disturbed the relative pool sizes of various amino acids resulting in a change in the genetically determined ratio at which amino acids were utilized for protein synthesis. Overproduction of alkaloids (4500 mug.ml-1) may be associated with increased availability of tryptophan because of the enhanced assimilation of asparagine-derived ammonia via glutamine synthetase (EC 6.3.1.2). However, ammonium salts in the fermentation broth led to a depression of the alkaloid yield. Partial replacement of the ammonium salt by aspartic acid elevated alkaloid production. |
