Immobilization of yeast cells containing ?-galactosidase

Abstract

Cultural conditions optimum for β‐galactosidase production by Saccharomyces anamensis are pH 4.5, temperature 26 ± 2°C, and 30 h of incubation period. Addition of lactose at 24 h fermentation greatly increase the level of enzyme. Optimum pHl, temperature, pH stability, and thermostability of yeast β‐galactosidase are negligibly affected by immobilization. The K_m values of enzyme in the native and immobilized cells are 102mM and 148mM, respectively. Glucose noncompetitively inhibits the enzyme activity. Addition of substances such as dithioerythritol, glutathione, and bovine serum albumin to the native cell during assay procedure and immobilized cell prior to immobilization have stimulatory effects on enzyme activity. Metal ions like Ca²⁺, Mg²⁺ enhance the β‐galactosidase activity for both intact and bound cells. Immobilized cells retain 68.6% of the β‐galactosidase activity of intact cells and there is no significant loss of activity on storage at 4°C for 28 days.