S-layer, a new support for enzyme immobilization

Abstract

The immobilization of enzymes has not been reported earlier on the two-dimensional crystalline bacterial cell surface (S-layer). In this study we tested S-layer isolated from Bacillus stearothermophilus PV72 for enzyme (s-glucosidase, hexokinase and aldolase) immobilization. The carbodiimide method gave yields less than 5%. The yields of co-cross-linking method with glutaraldehyde were enhanced compared to the carbodiimide method, but the yield was higher than 10% only in the case of s-glucosidase. Because of the fine structure of S-layer, immobilized enzymes could be removed from reaction mixtures only by centrifugation, therefore these preparations were entrapped in calcium alginate gel. The yields of entrapping procedures were between 15% and 37%. It was presumed that the new immobilized s-glucosidase preparation could be used in a preliminary testing for flavour enrichment of wines. Efficiency of this preparation was compared to that of the immobilized s-glucosidase on Acrylex C-100 support described earlier. We found that the immobilization of s-glucosidase on both Acrylex C-100 support and S-layer followed by gel entrapping resulted in active enzyme preparations that could be used for flavour enrichment of wines without enhancing their protein content.