A commercially available endo-inulinase from Aspergillus niger was successfully immobilized onto a chitin carrier with 66% yield. The immobilized endo-inulinase showed maximal activity at 65 °C that was 5 °C higher than the optimum temperature of the free enzyme. Also, the optimum pH shifted from 4.5 to 5.0 for free form and 5.5 to 6.0 for the immobilized form. The immobilized endo-inulinase was stable at 4 °C for at least 1 year. The residual activity of 90% and 95% of free and immobilized enzymes were recovered after 5 days of incubation without substrate at 60 °C and pH between 4.5 and 6.5. Kinetic parameters (Km and Vmax) for free and immobilized endo-inulinase were 2.04% (w/v) and 80.88 U/mg protein, and 2.19% (w/v) and 291.58 U/g support, respectively. The half-life time of immobilized endo-inulinase in a packed-bed column reactor was estimated to be 48 days. A continuous production system of inulo-oligosaccharides (IOS) from inulin and Jerusalem artichoke (JA) juice was set up and operated. Using this system, syrups with high IOS content (from 35% to 65%) were successfully prepared.
ASJC Scopus subject areas
- Applied Microbiology and Biotechnology