Two-Step Production of Neofructo-Oligosaccharides Using Immobilized Heterologous Aspergillus terreus 1F-Fructosyltransferase Expressed in Kluyveromyces lactis and Native Xanthophyllomyces dendrorhous G6-Fructosyltransferase

Burghardt Burghardt,Gerlach Gerlach,Czermak Czermak,Baas Baas

doi:10.3390/catal9080673

Abstract

Fructo-oligosaccharides (FOS) are prebiotic low-calorie sweeteners that are synthesized by the transfer of fructose units from sucrose by enzymes known as fructosyltransferases. If these enzymes generate β-(2,6) glycosidic bonds, the resulting oligosaccharides belong to the neoseries (neoFOS). Here, we characterized the properties of three different fructosyltransferases using a design of experiments approach based on response surface methodology with a D-optimal design. The reaction time, pH, temperature, and substrate concentration were used as parameters to predict three responses: The total enzyme activity, the concentration of neoFOS and the neoFOS yield relative to the initial concentration of sucrose. We also conducted immobilization studies to establish a cascade reaction for neoFOS production with two different fructosyltransferases, achieving a total FOS yield of 47.02 ± 3.02%. The resulting FOS mixture included 53.07 ± 1.66 mM neonystose (neo-GF3) and 20.8 ± 1.91 mM neo-GF4.

Highlights

Functional oligosaccharides possess health-promoting [1] and prebiotic properties [2]
The A. terreus 1-FFT expressed in K. lactis was produced at the 5-L scale in a Lafors 3 fermenter (Infors, Bottmingen, Switzerland) using adapted FM22 medium for cultivation [61]
G6 -FFT and A. terreus 1-FFT expressed in K. lactis

Summary

Introduction

Functional oligosaccharides possess health-promoting [1] and prebiotic properties [2]. The best known functional oligosaccharides are the fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), isomalto-oligosaccharides (IMOS) and xylo-oligosaccharides (XOS) [1,2,3] These diverse molecules differ in terms of their basic structure, the monosaccharides used for elongation and the chain length, resulting in a range of physicochemical and biological characteristics [1,2]. FOS are short-chain fructans, mainly consisting of fructose units, with a low calorific value [4,5,6,7,8] Their prebiotic effects reflect their ability to stimulate the growth of beneficial bifidobacteria and lactobacilli while inhibiting undesirable bacteria such as Clostridium perfringens [9,10,11,12]. FOS are mainly used as sugar substitutes [14,15], but their thickening properties and similar filling capacity to sucrose make them popular food additives [13]

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