Immobilization of Liquozyme X in Alginate beads

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Enzyme immobilization is one of the most important technologies used in food, pharmaceutical and biotechnology industries. Alpha-amylase immobilization is researched to increase the reusability of the enzyme and for continuous hydrolysis of starch in production of high fructose corn syrup. Liquozyme X, a genetically-engineered thermostable alpha-amylase, which is used in starch liquefaction due to lower pH stability and low calcium requirement (5-15ppm), is immobilized in calcium-alginate beads. Entrapment, surface adsorption, and covalent binding by using a cross-linking agent methods were tested for binding efficiency, remaining enzyme activity, and reusability at 95C. Km and Vmax values of the free Liquozyme X were 1mg/ml and 4.7mg starch degraded/ml * min, respectively, and 1.56mg/ml and 0.16mg starch degraded /ml * min for enzyme entrapped in alginate beads. The results showed that enzymes immobilized by entrapment and surface adsorption had low reusability due to enzyme leakage at high temperatures. After the initial use of the immobilized enzymes, the activity yield decreased from 16.47% to 3.2% for entrapped enzymes, and 23.4% to 2.1% for adsorbed enzymes after three uses. Cross-linking of the enzymes improved reusability but activity yield of the immobilized enzymes was reduced due to limited active sites available for starch degradation. The cross-linked entrapped enzymes had 0.64% of activity yield and remained approximately 0.42% after three uses at 95C. Adsorbed enzymes followed by cross-linking had 1.16% of activity yield and remained 0.43% after three reuses.



Immobilization, Alginate beads