Soluble cellodextrins (linear β-1,4-D-gluco-oligosaccharides) have interesting applications as ingredients for human and animal nutrition. Their bottom-up synthesis from glucose is promising for bulk production, but to ensure a completely water-soluble product via degree of polymerization (DP) control (DP ≤ 6) presents a challenge. Here, we show controlled polymerization of cellodextrins with DP centered at 3 - 5 (~95 wt.% of total product) from glucose and α-glucose 1-phosphate (αGlc1-P) using coupled cellobiose and cellodextrin phosphorylase. For the purpose of efficient synthesis, kinetic and thermodynamic restrictions upon αGlc1-P utilization were overcome (from 53% to ≥ 90% conversion) by in situ removal of the phosphate released via precipitation with Mg2+. The product DP was controlled by molar ratio of glucose/αGlc1-P (~0.25; 50 mM glucose) used in the reaction. As result, the yield of soluble cellodextrins was 3.3 g/g glucose attained at 30.0 g/L total product concentration and 97% theoretical utilization of the substrates used. In addition, completely insoluble cellodextrins (DP ~10) were synthesized by keeping the glucose concentration low (1 - 10 mM; 200 mM αGlc1-P). In summary, this study provides the basis for an efficient and product DP-controlled biocatalytic synthesis of cellodextrins from expedient substrates.
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 761030 (CARBAFIN).