Characterization of Crude Thermostable Exoinulinase Produced by Saccharomyces sp.

Abstract

Studies were carried out to investigate the properties of extracellular inulinase produced by Saccharomyces sp. in solid state fermentation of wheat bran. The pattern of inulin hydrolysis by the crude inulinase enzyme as revealed by thin layer chromatography analysis of the products of hydrolysis showed the inulinase to be exo-acting. Temperature and pH studies revealed that the inulinase preparation had an optimum activity of 125.4 units per gram of dry substrate (U/gds) at 50ºC while an optimum inulinase activity of 128.3 U/gds was observed at pH 4.5. The crude inulinase preparation retained 82% of its activity at 50ºC after heating for two hours. Effect of various thermal stabilizers on the activity of the crude inulinase showed that glycerol had the best thermal stabilizing effect on the activity of the crude inulinase preparation. Potassium and calcium ions were found to enhance the activity of the enzyme while mercury and silver ions completely inhibited the inulinase activity. The crude inulinase preparation had a Vmax and Km values of 416 and 1.47 mM, respectively.