Inulo-Oligosaccharides: Continuous Production from Inulin by Immobilized Inulinase from Aspergillus niger and in vitro Utilization by Bifidobacteria

Abstract

Endoinulinase was partially purified from the culture filtrate of a filamentous fungus Aspergillus niger mutant 817. The enzyme preparation was immobilized covalently onto a porous cellulose derivative, Amino-Cellulofine. A 5% (w/v) solution (pH 5.0) of pure dahlia inulin was fed continuously into a packed-bed column reactor containing the immobilized enzyme. The operating conditions were studied to produce a mixture of oligomers with a degree of polymerization of 3 to 5 by partial hydrolysis of inulin. Inulotriose (F₃) and -tetraose (F₄) were purified from the hydrolysis products by preparative high-performance liquid chromatography. In vitro studies indicated that both the F₃ and F₄ were preferentially utilized by Bifidobacterium spp., but not by Escherichia coli or Clostridium perfringens.