Ethanol fermentation by ionically adsorbed Zymomomas mobilis: Environmental effects on cell immobilization.

Batch ethanol fermentation by cells of Zymomomas mobilis ATCC 29191, ionically adsorbed on a DEAE-cellulose ion exchanger, was investigated in a stirred fermentor. Adsorption isotherms in different media were determined and used to interpret the effects of the environment on cell immobilization. Other factors affecting cell immobilization during an actual fermentation were studied. Mechanical agitation was found to cause detachment of cells from the ion exchange particles. The results suggest that the amount of cells adsorbed during a fermentation process is different from that found from adsorption isotherm data. Consequently, application of equilibrium adsorption data to actual fermentations should be done with caution.