Adsorption of the inulinase from Kluyveromyces marxianus NRRL Y-7571 on Streamline® DEAE resin

Abstract

The enzyme inulinase is used to produce oligosaccharides and fructose, with up to 95% fructose in a single stage of inulina hydrolysis. With in the aim to purify the enzyme, studies on the conditions of enzyme adsorption in an expanded-bed column were conducted using phosphate and tris-HCl buffers. The inulinase used in this work was obtained from Kluyveromyces marxianus NRRL Y-7571 by fermentation in an industrial medium. Using the anionic resin Streamline DEAE, the adsorption equilibrium time was determined. It was observed that the adsorption isotherm follows the Langmuir model; the parameters for the maximum amount of adsorbed inulinase (Qm) and the dissociation constant (k d) were determined. With 0.05 M sodium phosphate buffer at pH 6.0, the parameter values 1428 UI/mL and 2 UI/mL with a correlation coefficient of 0.96 were obtained. For 0.02 M tris-HCl buffer at pH 7.5, the same parameters were 5000 UI/mL and 0.05 UI/mL with a correlation coefficient of 0.99. The best purification conditions for the fixed bed were shown to be a 0.4 M phosphate buffer with NaCl as eluter, a purification factor of 11.4, and a recovery yield of up to 79%.