Novel biotechnological glucosylation of high-impact aroma chemicals, 3(2H)- and 2(5H)-furanones

Abstract

Glucosyltransferases are versatile biocatalysts to chemically modify small molecules and thus enhance their water solubility and structural stability. Although the genomes of all organisms harbor a multitude of glucosyltransferase genes, their functional characterization is hampered by the lack of high-throughput in-vivo systems to rapidly test the versatility of the encoded proteins. We have developed and applied a high-throughput whole cell biotransformation system to screen a plant glucosyltransferase library. As proof of principle, we identified 25, 24, 15, and 18 biocatalysts transferring D-glucose to sotolone, maple furanone, furaneol and homofuraneol, four highly appreciated flavor compounds, respectively. Although these 3(2H)- and 2(5H)-furanones have extremely low odor thresholds their glucosides were odorless. Upscaling of the biotechnological process yielded titers of 5.3 and 7.2 g/L for the new to nature β-D-glucopyranosides of sotolone and maple furanone, respectively. Consequently, plant glucosyltransferase show stunning catalytic activities, which enable the economical production of novel and unexplored chemicals with exciting new functionalities by whole-cell biotransformation.

Glycosylation of bioactive C13-apocarotenols in Nicotiana benthamiana and Mentha × piperita

“…Table S1). Similarly, biocatalyst for the production of the C 13 -apocarotenyl glucoside according to (Effenberger et al 2019). The NMR data confirmed the structure of the product (Supplemental Figure S4) and were in accordance with those of (Zeng et al 2014).…”

“…The glucoside produced by the whole-cell biocatalyst could be readily purified by solid phase extraction from the supernatant of the culture. After distillation and ethyl acetate extraction, the colored impurities were removed by activated carbon treatment (Effenberger et al 2019). LC-MS and NMR analyses confirmed purity and identity, respectively (Supplemental Figure S4).…”

“…Whole cell biotransformation was performed according to the procedure in (Effenberger et al 2019) using MpUGT86C10-pGEX-4T1 for the production of α-ionyl β-D-glucopyranoside, except that a 5-L-bioreactor was used. Bacteria were grown at 37 °C in M9 minimal medium to an OD 600 of 1.5.…”

Chemical and Sensory Characteristics of Soy Sauce: A Review

“…When sotolone is present at low concentrations, it is known to have a caramel, burnt sugar aroma. 74 Different precursors and reaction pathways have been proposed for its (bio)synthesis, but its formation mechanism in soy sauce has not yet been elucidated. 75 Sotolone has been described as the flavor principle of food prepared from plant protein hydrolysates.…”

“…75 Sotolone has been described as the flavor principle of food prepared from plant protein hydrolysates. 74 Furthermore, sotolone rapidly decomposes at temperatures above 80 °C, 76 which explains its significant decrease and the loss of the seasoning-like aroma note when heat treatments (cooking) have been used. 54 …”