Inulinase from Rhodotorula mucilaginosa: immobilization and application in the production of fructooligosaccharides

Abstract

The crude extract containing inulinase from Rhodotorula mucilaginosa was obtained by submerged fermentation. Inulinase was immobilized on chicken eggshell by physical adsorption and covalent crosslinking, using glutaraldehyde as a crosslinking reagent, and Celite by adsorption. Fructooligosaccharides production was performed using immobilized inulinase (5%, w/v) and inulin substrate solution under experimental conditions evaluated through Doehlert experimental design. The production of inulinase was optimized for concentrations of D-glucose and yeast extract at 12.5 and 0.5 g/L, respectively, resulting in an optimal activity of 0.62 U. The optimal pH and temperature for enzyme activity were 8.0 and 75°C, respectively, leading to an optimal activity of 3.54 U. The highest immobilization efficiency (46.27%) was obtained upon immobilization on Celite. Immobilization by adsorption to eggshell allowed for specific activity of 4.15 U/g, and adsorption to Celite resulted in specific activity of 3.70 U/g. The highest titer in fructooligosaccharides was obtained with an initial inulin concentration of 250 g/L (25%, w/v), and a reaction time of 16 h. Hence, immobilized inulinase proved to be a promising catalyst for fructooligosaccharides production since the formulation is performed through a simple, low-cost, and large-scale applicable methodology.

Rhodotorula Mucilaginosa: Two Faces of the Yeast

“…Immobilized inulinase (5%, w/v) on chicken eggshell was successfully used to produce fructooligosaccharides from inulin substrate solution. The maximal activity of this enzyme was 3.54 U at optimal pH 8.0 and temperature 75 o C [16].…”

Production, purification, and characterization of inulinase from Streptomyces anulatus

“…Since it is abundantly available in nature and its main composition is fructose, it can be used as a substrate in the production of fructo-oligosaccharides and high-fructose syrup for food, pharmaceutical, and beverage industries [3]. Fructose can be extracted by acid hydrolysis of inulin, but fructose is easily degraded at low pH and the process leads to discoloration of the inulin hydrolysate and by-product formation in difructose anhydride form [1,[4][5][6][7]. Another method uses microbial sources, which secrete a large amount of inulinase and can cleave fructose from inulin, in a one-step catalyzed reaction with yields up to 95% fructose [8,9].…”