Discovery of a Novel Sucrose 6F-Phosphate Phosphorylase and Its Application for Isomelezitose Production

Rare sugars have gained attention as attractive alternatives to conventional sugars due to their potential health benefits and lower caloric value. However, their scarcity restricts widespread application, highlighting the need for efficient biosynthetic production strategies. In this study, a novel sucrose 6F-phosphate phosphorylase from Sphaerochaeta globosa strain Buddy was identified through sequence analysis within the glycoside hydrolase family GH13_18. Substrate screening revealed that this enzyme is capable of producing isomelezitose, a rare trisaccharide naturally found in honey, known for its osmoprotective and potential prebiotic properties. A proof-of-concept production at a 1 L scale, starting from cheap bulk sugars sucrose and isomaltulose, yielded 68 g of high-purity isomelezitose (>99%), which enabled a first evaluation of its properties as a food ingredient. Isomelezitose exhibited limited digestibility and a relative sweetness of 27% compared to sucrose. Moreover, its physicochemical properties were comparable to those of sucrose, including similar glass transition temperature, crystallinity, and flow/tribological behavior. To this end, isomelezitose might form an interesting opportunity as a sugar alternative in the food industry.