Immobilization and characterization of inulinase from Ulocladium atrum on nonwoven fabrics

Ulocladium atrum inulinase was immobilized on different composite membranes composed of chitosan/nonwoven fabrics. Km values of free and immobilized U. atrum inulinase on different composite membranes were calculated. The enzyme had optimum pH at 5.6 for free and immobilized U atrum inulinase on polyester nonwoven fabric coated with 3% chitosan solution (PPNWF3), but optimum pH was 5 for immobilized U atrum inulinase on polyester and polypropylene nonwoven fabrics coated with 1% chitosan solution. The enzyme had optimum temperature at 40 degrees C for immobilized enzyme on each of polyester and polypropylene composite membranes coated with 1% chitosan, while it was 50 degrees C for free and immobilized enzyme on polypropylene nonwoven fabric coated with 3% chitosan solution. Free atrum inulinase was stable at 40 degrees C but thermal stability of the immobilized enzyme was detected up to 60 degrees C. Reusability of immobilized enzyme was from 38 to 42 cycles of reuse; after this, the immobilized enzyme lost its activity completely. In conclusion, immobilized U atrum inulinase was considerably more stable than the free enzyme, and could be stored for extended periods.