Chemical characterization of levan and optimization of immobilized bacillus tequilensis levansucrase onto κ-Carrageenan –CMC Gel Beads

Abstract

BACILLUS (130 g/L).tequilens The levanwas yielda wasgood characterizedlevansucrase byproducer FT-IR and(222.2 theU/mL) results recordedwith levan thatyield 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 polyethylenimine followed by glutaraldehyde. Then 22 full-factorial central composite experiment design was employed to optimize the conditions for the maximum enzyme loading efficiency to reach (14.01852 U/g gel beads). The free enzyme showed optimum activity at pH7 while, immobilization process increased the tolerance of enzyme at both acidic range pH3 and alkaline range pH10. The apparent Km after immobilization was 2.85 mg/mL compared to 2.5 mg/mL for free enzyme. Maximum velocity V max was 71.4 mg/min for free enzyme while it was 62.4 mg/min for immobilized formula of enzyme. An inhibition of enzyme activity was recognized with all tested metal ion as well as EDTA for either free or immobilized formula of levansucrase.