MECHANICAL STABILITY AND DIFFUSIONAL RESISTANCE OF A POLYMERIC GEL USED FOR BIOCATALYST IMMOBILIZATION

The mechanical strength of gelatin gels insolubilized by crosslinking with formaldehyde was measured at various gelatin percentages and formaldehyde-to-gelatin ratios. This property was shown to be related to the characteristic sponge-like structure of the insolubilized gelatin gel, a structure that unexpectedly is also responsible for the resistance to substrate and product diffusion. A comparison between immobilizates of invertase and invertase-active yeast cells prepared with different gelatin concentrations showed that the enzyme, in contrast to cells, is deeply involved in the gel insolubilization process. The catalytic behavior of agar, κ-carrageenan, alginate, and gelatin immobilizates was compared under the same conditions of cell loading. © 1990.