Alkaloid production by immobilized mycelia of Claviceps purpurea

Abstract

Mycelia of Claviceps purpurea CBS 164.59 which produce clavine alkaloids and ergometrine were immobilized in different matrices. These mycelia exhibited a high sensitivity to extreme physical and chemical treatment, and only a moderate immobilization in calcium alginate proved to be the appropriate method to yield high alkaloid amounts. The alkaloid production is correlated to the amount of biomass. The patterns of alkaloid yields of 4% calcium alginate immobilized cells, compared to free cells, were reduced but not shifted in their maximum. With increasing calcium alginate concentrations (5%–8%) an increase of the alkaloid production even higher than that of free mycelia could be observed. Immobilization of mycelia in 8% calcium alginate resulted in a 35% increase (mg alkaloids/l medium) in overall alkaloid production. Because of reduced O2-diffusion into the beads, high calcium alginate concentrations induced a shift in the clavine alkaloid production: 8% calcium alginate immobilized cells produced agroclavine as main product whereas free cells oxidized agroclavine with molecular oxygen to produce elymoclavine and excreted this alkaloid as main product.