Efficient production of inulooligosaccharides from inulin by endoinulinase from Aspergillus arachidicola. (15th March 2019) - Jiang, Xiangling
Highlights: An endoinulinase was characterized from Aspergillus arachidicola . The optimum pH and temperature were pH 5.5 and 60 °C. DP3 and DP4 were produced as major products during inulin endohydrolysis. The conversion yield of inulin to inulooligosaccharides reached 60–90%. Yeast treatment was first developed to improve the inulooligosaccharides purity. Abstract: Inulin has been widely used as a cheap material to produce many valuable products such as inulooligosaccharides. In this study, an inulooligosaccharide-producing endoinulinase was identified from Aspergillus arachidicola . The gene encoding the mature endoinulinase was cloned and intracellularly overexpressed in Escherichia coli . The recombinant endoinulinase was purified by nickel affinity chromatography. The optimum pH and temperature were pH 5.5 and 60 °C, respectively. It was highly thermostable at up to 55 °C for 2 h, however easily inactivated at higher temperatures. The enzyme efficiently produced inulooligosaccharides from inulin, with inulotriose and inulotetraose as major products. When 10, 30, 50, and 100 g L −1 of inulin was used as substrate, the final conversion ratio of total inulooligosaccharides reached 88.4%, 83.5%, 80.2%, and 60.1%, respectively. In addition, yeast treatment was first developed to improve the inulooligosaccharides purity by specifically consuming sucrose and monosaccharides without any losses in inulooligosaccharides content.