Adsorptive immobilization of enzymatic active substances on alumina–silica foam coated by carbon nanofibers

The adsorption abilities of an alumina–silica foam coated by a layer of catalytic filamentous carbon (CFC/ceramics) were studied with respect to enzymatic active substances (EAS) - enzymes glucoamylase and invertase, intracellular compartments of baker’s yeast and whole non-growing cells of various microorganisms (Saccharomyces cerevisiae, Rhodococcus sp., Arthrobacter sp.). The activity and stability of heterogeneous biocatalysts prepared by EAS adsorption on the CFC/ceramics were studied in hydrolysis, oxidation and isomerization reactions. Glucoamylase was found to retain up to 20% of the activity of a soluble enzyme after adsorption on the CFC/ceramics. Invertase and invertase-active yeast autolysate retained practically all their activity. The enzymatic activities of non-growing cells of baker’s yeast and Rhodococcus increased after adsorption on CFC/ceramics by a factor of 1.5–1.8 and 3.7, respectively. A “glucoamylase on CFC/ceramics” biocatalyst for the hydrolysis of dextrin was shown to have high long-term stability, retaining its activity after storage for 10–12 months at ambient temperature. A “yeast autolysate on CFC/ceramics” biocatalyst for sucrose inversion retained >50% of the activity after 2–3 month storage at ambient temperature. A “non-growing bacteria Arthrobacter sp. on CFC/ceramics” biocatalyst for glucose isomerization retained half its activity after 12 h use at 70 °C.