Relationship between the Claviceps Life Cycle and Productivity of Ergot Alkaloids

Abstract

The morphology, biochemistry, and physiology studies during development of Claviceps purpurea fungi clearly demonstrate that alkaloid synthesis is linked to a specific stage of the fungal life cycle. In nature, ergot alkaloids are synthesized in the course of developing sclerotia, while in submerged cultures, lacking sexual reproduction, alkaloid synthesis proceeds in sclerotia-like cells. Highly active submerged strains could be obtained by combination of mutagens with a different mode of action as well as by somatic hyphal anastomoses or efficient protoplast fusions to obtain the parasexual cycle. Fused strains not only retained the biosynthetic activity of parent strains but produced even much higher amounts of alkaloids. In our strains, the appropriate morphology always corresponded to high productivity. Furthermore, the form of cell differentiation was typical for each particular strain. When comparing active and inactive strains, measurements of qualitative and quantitative changes in mycelium composition revealed different metabolic patterns and certain characteristics necessary for efficient alkaloid production. Evaluation of activities of some enzymes from the central metabolic pathways, which generate the basic intermediates for ergot alkaloid synthesis also contributed to the overall knowledge of mechanisms involved.