Chemical Characterization of Levan and Optimization of immobilized Bacillus tequilensis levansucrase onto κ-Carrageenan –CMC Gel Beads

Document Type : Original Article


1 Chemistry of Microbial and Natural ProductsDepartment, National Research Centre (NRC); Dokki, Cairo, Egypt.

2 Centre of Excellence, Encapsulation Nanobiotechnology Group, National Research Centre, Dokki, Cairo, Egypt.

3 Department of Microbiology, Faculty of Science, Ain Shams Univ., Cairo, Egypt.


acillus tequilens was a good levansucrase producer (222.2 U/mL) with levan yield (130 g/L). The levan yield was characterized by FT-IR and the results recorded that the product was mainly fructose. Levansucrase produced by Bacillus tequilens was immobilized by covalent binding on κ-carrageenan and carboxy methyl cellulose gel beads activated by two-step method; the gel beads were soaked in polyethyleneimine followed by glutaraldehyde. Then22 full-factorial central composite experiment designs were employed to optimize the conditions for the maximum enzyme loading efficiency to reach (14.01852 U/of enzyme/g gel beads).The free enzyme showed optimum pH at7 while immobilization process increased the tolerance of enzyme at both alkaline range pH3 and acidic range pH10. The apparent Km after immobilization was 2.85 mg/mL compared to 2.5 mg/mL for free enzyme. Maximum velocity Vmax was 71.4 mg.min−1 for free enzyme while it was 62.4 mg.min−1 for immobilized formula of enzyme. An inhibition of enzyme activity was recognized with all tested metal ion as well as EDETA for either free or immobilized formula of levansucrase.


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