Fungal secondary metabolites of considerable pharmaceutical interest are the ergot alkaloids produced by the pyrenomycete Claviceps. Living parasitically on grain Claviceps cells form sclerotia with plectenchymatic structures of high alkaloid content. Saprophytically cultured Claviceps mycelia form sclerotia-like cells at the end of the growth phase, and the alkaloid production is strongly related to this morphological differentiation and a change in metabolism. Mycelia of Claviceps are sensitive to mechanical stress and local oxygen deicits and show strong tendency to degeneration. Thus the saprophytic culturing in scaled-up fermenters with conventional microbiological methods presents dificulties. Application of the immobilization technique should stabilize the metabolic activity of the mycelia and thus lead to an increased and continuous alkaloid production. This paper describes the batch and semicontinuous fermentation of calcium alginate-immobilized Clauiceps purpurea under various conditions. Parts of the following investigations have been described previouslyla-3 and are summarized in this article. The following results and morphological considerations indicate that immobilization techniques perhaps simulate the conditions of parasitically formed Clauiceps sclerotia and thus lead to increased and prolonged alkaloid production.
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