Immobilization of Saccharomyces diastaticus on wood chips for ethanol production.

Saccharomyces diastaticus cells were immobilized onto beech wood chips of different particle size and three pH values. pH values in the range 5.0-6.0, and 1.84-1.92 mm particle size had a positive effect on the immobilization process. The chosen carrier--1.84 mm-sized wood chips adsorbed 150 mg dry cell mass per g dry carrier mass. The Gibbs free energy and the activation energy for the first (monolayer) and second (multilayer) immobilization stages was 4581, 19,090 and 8590 J g mol-1, respectively. The kinetics of immobilized cell systems in ethanol production have been studied in a packed bed-reactor. Ethanol production and the respiration quotient (RQ) were at a maximum at a dilution rate of 0.16/h. The reactor was operated under steady-state conditions for 30 d at the dilution rate 0.16/h.