Repeated batch production of ethanol from Jerusalem artichoke tubers using recycled immobilized cells of Kluyveromyces fragilis

Abstract

Recycled immobilized cells of Kluyveromyces fragilis ATCC 28244 were used for repeated batch production of ethanol from the inulin sugars derived from Jerusalem artichoke tubers. Using 10% initial sugar concentration, a maximum ethanol concentration of 48 g/l was achieved in 7 h when the immobilized cell concentration in the Ca alginate beads was 72 g dry wt. immobilized cell/l bead volume. The maximum ethanol production rate was 13.5 g ethanol/l bioreactor volume/h. The same Ca alginate beads containing the cells were used repeatedly for 11 batch runs starting with fresh medium at the beginning of each run. The ethanol yield was found to be almost constant at 96% of the theoretical for all 11 batch runs, while the maximum ethanol production rate during the last batch run was found to be 70% of the original ethanol rate obtained in the first batch run.