Hidenao Saito

Ethanol production by repeated batch culture using yeast cells immobilized within porous cellulose carriers.

Ethanol was efficiently produced for 20 d by repeated batch culture using yeast cells immobilized in porous cellulose carriers. The physical structure of the carrier beads, which had small pores distributed on the outer surface and relatively large pores distributed in the interior, was found to be effective for cell immobilization. The effects of chemical modifications to the basic cellulose carrier on cell immobilization and ethanol production were also examined in repeated batch cultures. The chemical modifications had little effect on either cell immobilization or ethanol production.

Citric Acid Production by Aspergillus niger Immobilised on Porous Cellulose Beads

Citric acid production using immobilised Aspergillus niger was studied. For the immobilisation, Viscopearl (porous cellulose beads) was used as the carrier. The immobilised ratio of the biomass to the carrier was controlled by changing the preculture periods. It significantly affected the production rate, the yield and the maximum concentration of citric acid. The optimum value of the preculture periods was 3 days in relation to the citric acid production. The initial sugar concentration also affected the citric acid production, and the optimum value was 100 g dm−3. Furthermore, the repeated batch culture was carried out using the immobilised biomass at several batch intervals. The optimum values of the batch interval were 6 days for the citric acid productivity and 8 days for the most cost effective process.