Affordable Access

Glucansucrase (mutant) enzymes from Lactobacillus reuteri 180 efficiently transglucosylate Stevia component rebaudioside A, resulting in a superior taste

Authors
  • te Poele, Evelien M
  • Devlamynck, Tim
  • Jäger, Manuel
  • Gerwig, Gerrit J
  • Van de Walle, Davy
  • Dewettinck, Koen
  • Hirsch, Anna KH
  • Kamerling, Johannis P
  • Soetaert, Wim
  • Dijkhuizen, Lubbert
Publication Date
Jan 01, 2018
Source
Ghent University Institutional Archive
Keywords
Language
English
License
Unknown
External links

Abstract

Steviol glycosides from the leaves of the plant Stevia rebaudiana are high-potency natural sweeteners but suffer from a lingering bitterness. The Lactobacillus reuteri 180 wild-type glucansucrase Gtf180-Delta N, and in particular its Q1140E-mutant, efficiently alpha-glucosylated rebaudioside A (RebA), using sucrose as donor substrate. Structural analysis of the products by MALDI-TOF mass spectrometry, methylation analysis and NMR spectroscopy showed that both enzymes exclusively glucosylate the Glc(beta 1 -> C-19 residue of RebA, with the initial formation of an (alpha 1 -> 6) linkage. Docking of RebA in the active site of the enzyme revealed that only the steviol C-19 beta-D-glucosyl moiety is available for glucosylation. Response surface methodology was applied to optimize the Gtf180-Delta N-Q1140E-catalyzed a-glucosylation of RebA, resulting in a highly productive process with a RebA conversion of 95% and a production of 115 g/L alpha-glucosylated products within 3 h. Development of a fed-batch reaction allowed further suppression of alpha-glucan synthesis which improved the product yield to 270 g/L. Sensory analysis by a trained panel revealed that glucosylated RebA products show a significant reduction in bitterness, resulting in a superior taste profile compared to RebA. The Gtf180-Delta N-Q1140E glucansucrase mutant enzyme thus is an efficient biocatalyst for generating a-glucosylated RebA variants with improved edulcorant/organoleptic properties.

Report this publication

Statistics

Seen <100 times