Glucansucrase (mutant) enzymes from Lactobacillus reuteri 180 efficiently transglucosylate Stevia component rebaudioside A, resulting in a superior tasteTe Poele, E. M., Devlamynck, T., Jäger, M., Gerwig, G. J., Van de Walle, D., Dewettinck, K., Hirsch, A. K. H., Kamerling, J. P., Soetaert, W. & Dijkhuizen, L., 24-Jan-2018, In : Scientific Reports. 8, 1, 12 p., 1516.
Research output: Contribution to journal › Article › Academic › peer-review
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-ΔN, and in particular its Q1140E-mutant, efficiently α-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(β1→C-19 residue of RebA, with the initial formation of an (α1→6) linkage. Docking of RebA in the active site of the enzyme revealed that only the steviol C-19 β-D-glucosyl moiety is available for glucosylation. Response surface methodology was applied to optimize the Gtf180-ΔN-Q1140E-catalyzed α-glucosylation of RebA, resulting in a highly productive process with a RebA conversion of 95% and a production of 115 g/L α-glucosylated products within 3 h. Development of a fed-batch reaction allowed further suppression of α-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-ΔN-Q1140E glucansucrase mutant enzyme thus is an efficient biocatalyst for generating α-glucosylated RebA variants with improved edulcorant/organoleptic properties.
|Number of pages||12|
|Publication status||Published - 24-Jan-2018|
- Glucansucrase enzymes, Lactobacillus reuteri 180, Stevia, rebaudioside A, mutant enzymes, ENZYMATIC TRANSGLUCOSYLATION, STRUCTURAL-CHARACTERIZATION, STEVIOSIDE, SWEET, GTF180, GLYCOSIDES, RUBUSOSIDE, REBAUDIANA, GLUCAN, CYCLODEXTRIN