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Cellulase Immobilization on Ca-alginate Beads

Primož Plahuta1 and Peter Raspor2*

1Agroind »VIPAVA 1894«, Vinarska cesta 5, Vipava, 5271, Slovenia
2Chair of Biotechnology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia

Article history:

Received February 2, 1996 
Accepted June 18, 1996

Key words:

cellulase immobilization, Ca-alginate, lactitol, DEAE-dextran

Summary:
Cellulase (EC 3.2.1.4) was immobilized on inactivated baker's yeast biomass which was trapped in Ca-alginate beads. The specific enzyme activity of free cellulase was 4.72 U/mg protein, while the specific enzyme activity of the immobilized enzyme was 0.56 U/mg protein. The pH optimum of free cellulase was at pH=3.5 and of the immobilized one was at pH=3.0. The immobilized enzyme had a high relative activity over the whole examined pH range which is of great technological importance. The temperature optimum for the free enzyme was between 37 and 60 °C, while the temperature optimum of the immobilized enzyme was found at 60 °C. Free and immobilized enzyme stabilities during 2-hour incubation at 70 °C were very similar. At the end of incubation the initial enzyme activity was drastically reduced. The lime profile of enzyme activity showed thai immobilized enzyme stored in 0.01 M acetate buffer at 4 °C lost its enzyme activity after 9 days, while in 0.1 M phosphate buffer with DEAE-dexiran and lactitol at the same temperature the Ca-alginate beads still had some enzyme activity after 45 days.