Abstract
Effect of diffusion resistance on reaction by using an immobilized yeast entrapped by Ca-alginate gel was studied. Intraparticle effective diffusivity of substrate, De, depends upon cell density, cc, i.e. De/Do = k2(1 - k1cc)2. Here, D0 is a reference diffusivity, e.g. diffusivity in water; k1 and k2 are constants. Overall reaction rates of ethanol production by immobilized resting-yeast were measured. Experimental rates coincide well with calculated results using the effective diffusivity and reaction rate of free cells. Diffusion seemed to be restricted by cells. Thus large cell density does hot necessarily mean high reactivity. Finally, the curvature of the Lineweaver-Burk plot is pointed out.
