Controlled production of fructose by an exoinulinase from Aspergillus ficuum

Appl Biochem Biotechnol. 2009 Oct;159(1):65-77. doi: 10.1007/s12010-008-8479-6. Epub 2009 Jan 6.

Abstract

An exoinulinase has been isolated, purified and characterised from a commercially available broth of Aspergillus ficuum. The enzyme was purified 4.2-fold in a 21% yield with a specific activity of 12,300 U mg(-1)(protein) after dialysis, ammonium sulphate fractionation and Sephacryl S-200 size exclusion and ion exchange chromatography. The molecular weight of this enzyme was estimated to be 63 kDa by SDS-PAGE. It exhibited a pH and temperature optima of 5.4 and 50 degrees C respectively and under such conditions the enzyme remained stable with 96% and 63.8% residual activity after incubation for 12 h and 72 h respectively. The respective K (m) and V (max) values were 4.75 mM and 833.3 micromol min(-1) ml(-1), respectively. Response surface methodological statistical analysis was evaluated for the maximal production of fructose from the hydrolysis of pure commercial chicory inulin. Incubation of the dialyzed crude exoinulinase (100 U/ml, 48 h, 50 degrees C, 150% inulin, pH 5.0) produced the highest amount of fructose (106.4 mg/ml) under static batch conditions. The purified exoinulinase was evaluated for fructose production and the highest amount (98 mg/ml) was produced after 12 h incubation at 50 degrees C, 150% inulin pH 5.0. The use of a crude exoinulinase preparation is economically desirable and the industrial production of fructose from inulin hydrolysis is biotechnologically feasible.

MeSH terms

  • Aspergillus / enzymology*
  • Computer Simulation
  • Enzyme Activation
  • Enzyme Stability
  • Fructose / chemical synthesis*
  • Glycoside Hydrolases / chemistry*
  • Inulin / chemistry*
  • Models, Chemical*

Substances

  • Fructose
  • Inulin
  • Glycoside Hydrolases
  • inulinase