Passive immobilization of Aspergillus awamori spores for subsequent glucoamylase production

Production of glucoamylase using immobilized cells of Aspergillus awamori has been studied in batch and repeated batch fermentations and compared with free cell production. Immobilization was achieved passively, in situ, by using cubes of reticulated polyurethane foam (BSPs). Spores of the organism were inoculated into liquid medium containing the foam BSPs and became immobilized prior to or during germination. The subsequent mycelial growth remained immobilized until the particles eventually became overgrown with biomass. Enzyme production by mycelia grown from immobilized spores during batch fermentation was comparable to that of free cells, with enzyme concentration reaching approximately 33 IU cm-3 by the end of the batch period. In preliminary repeated batch experiments, successful reuse of the immobilized cells was achieved, with comparable levels of enzyme production being maintained for three batch cycles.