Innovative application of a novel di-d-fructofuranose 1,2′:2,3′-dianhydride hydrolase (DFA-IIIase) from Duffyella gerundensis A4 to burdock root to improve nutrition

Abstract

Burdock is native to Europe and Asia and rich in many functional ingredients, including biomacromolecule polysaccharide inulin. The prebiotic fructan inulin can provide energy to organisms via several pathways. One pathway is that inulin fructotransferase (IFTase) first converts inulin to III-type difructose anhydride (DFA-III), which has many beneficial physiological functions. Then, DFA-III is hydrolyzed to inulobiose, which is a F_n-type prebiotic fructo-oligosaccharide, via difructose anhydride hydrolase (DFA-IIIase). However, there has been no study on the application of IFTase or DFA-IIIase to process burdock to increase DFA-III or inulobiose. Moreover, only five DFA-IIIases have been reported to date and all of them are from the Arthrobacter genus. Whether other microbes except for the Arthrobacter genus can utilize DFA-III through DFA-IIIase is unknown. In this work, a DFA-IIIase from Duffyella gerundensis A4 (D. gerundensis A4), abbreviated as DgDFA-IIIase, was identified and characterized in detail. DgDFA-IIIase is a bifunctional enzyme, that is, besides its hydrolytic ability to DFA-III, it has the same catalytic ability as IFTase to inulin. The enzyme was applied to the burdock root aiming at inulin and DFA-III, and inulobiose was produced with an increase in G_n-type fructo-oligosaccharide. The work verifies that microorganisms of the non-Arthrobacter genus also have the potential ability to use DFA-III by DFA-IIIase, and DFA-IIIase is feasible to increase functional substances of burdock root instead of IFTase and endo-inulinase, which paves the way for the production of functional food utilizing the polysaccharide inulin to improve nutrition and health.