Efficient Biosynthesis of Theanderose, a Potent Prebiotic, Using Amylosucrase from <i>Deinococcus deserti</i>

The study aimed to develop an efficient bioprocess for the discovery and synthesis of theanderose by using amylosucrase from <i>Deinococcus deserti</i> (<i>Dd</i>AS). An unknown trisaccharide produced by <i>Dd</i>AS was detected by high-performance anion-exchange chromatography-pulsed amperometric detection and high-performance liquid chromatography-evaporative light scattering detection, purified using medium-pressure liquid chromatography, and identified as theanderose (α-d-glucopyranosyl-(1→6)-α-d-glucopyranosyl-(1→2)-β-d-fructofuranoside) through nuclear magnetic resonance and mass spectrometry. <i>Dd</i>AS synthesized theanderose with a 25.4% yield (174.1 g/L) using 2.0 M sucrose at 40 °C for 96 h. In an in vitro digestion model, theanderose showed a 6.5% hydrolysis rate over 16 h. Prebiotic efficacy tests confirmed that theanderose significantly enhanced the proliferation of selected <i>Bifidobacterium</i> strains in the culturing medium with theanderose as the main carbon source. Subsequently, fecal fermentation was performed by adding theanderose to the feces of 20 individuals of varying ages to assess its effect on the gut microbiota. Theanderose increased the relative abundance of <i>Bifidobacteriaceae</i> and <i>Prevotellaceae</i> while decreasing the population ratio of <i>Lachnospiraceae</i> and <i>Ruminococcaceae</i>. Conclusively, theanderose displayed excellent prebiotic potential when judged by low digestibility and selective growth of beneficial microbes over harmful microbes.