Strategies for the synthesis of the osmolyte glucosylglycerate and its precursor glycerate

Abstract

Glycosidic osmolytes are widespread natural compounds that protect microorganisms and their macromolecules from the deleterious effects of various environmental stresses. Their protective properties have attracted considerable interest for industrial applications, especially as active ingredients in cosmetics and healthcare products. In that regard, the osmolyte glucosylglycerate is somewhat overlooked. Glucosylglycerate is typically accumulated by certain organisms when they are exposed to high salinity and nitrogen starvation, and its potent stabilizing effects have been demonstrated in vitro. However, the applications of this osmolyte have not been thoroughly explored due to the lack of a cost-efficient production process. Here, we present an overview of the progress that has been made in developing promising strategies for the synthesis of glucosylglycerate and its precursor glycerate, and discuss the remaining challenges. KEY POINTS: • Bacterial milking could be explored for fermentative production of glucosylglycerate • Glycoside phosphorylases of GH13_18 represent attractive alternatives for biocatalytic production • Conversion of glycerol with alditol oxidase is a promising strategy for generating the precursor glycerate.

Keywords: Glucosylglycerate; Glycerate; Osmolyte; Sucrose phosphorylase.

Fig. 1

Reactions catalyzed by phosphorylases for the synthesis of 2-O-α-glucosyl-d-glycerate. a One-step transglucosylation performed by LmSP or XpGP, b cascade reaction with SP and GGaP, where glucose 1-phosphate acts as intermediate. (Fru: fructose, Pi: inorganic phosphate, SP: sucrose phosphorylase, GGaP: glucosylglycerate phosphorylase: d-GA: d-glycerate)

Fig. 2

Schematic representation of the several biotechnological routes for d-glycerate synthesis. Blue denotes the strategies based on the valorization of glycerol, while green indicates approaches based on alternative substrates. (AldO: alditol oxidase, mADH: membrane-bound alcohol dehydrogenase, mALDH: membrane-bound aldehyde dehydrogenase, GAH: glyceraldehyde, FAD: flavin adenine dinucleotide)