Freeze-dried Saccharomyces cerevisiae cells immobilized on gluten pellets for glucose fermentation

No protecting medium was used for the freeze-drying of Saccharomyces cerevi siae free cells and those immobilized on gluten pellets to form an immobili zed biocatalyst. The use of these for glucose fermentations at various init ial glucose concentrations, temperatures and initial pH values showed that the fermentation time for the first batch with freeze-dried immobilized cel ls was 1.5- to 3-fold less than that with free freeze-dried cells. In the s econd repeated batch, the fermentation time of freeze-dried immobilized cel ls was less, in some cases up to three times less than the first batch and reached the fermentation time of fresh immobilized cells. After storage for 16 months at 4 degreesC, freeze-dried immobilized biocatalyst was used for five repeated batch fermentations of glucose. The fermentation time decrea sed continuously until 18 h, which was less than the half of the fermentati on time of the first batch. (C) 2001 Elsevier Science Ltd. All rights reser ved.