Transformation of formaldehyde into functional sugars via multi-enzyme stepwise cascade catalysis†
The bioconversion of one-carbon compounds into high-value products is important in the energy and chemical fields. In this study, two one-pot multi-enzyme reaction systems were constructed using known formolase and aldolase to synthesise stereodefined functional sugars directly from the prebiotic compound formaldehyde. A stepwise cascade biocatalysis approach was employed, and it decreased the byproduct formation and increased the conversion rate of L-erythrulose from 85% to 91% and L-sorbose from 0 to 68%. This approach was also employed in the whole-cell transformation of low-carbon units, such as formaldehyde, glycolaldehyde, and dihydroxyacetone, and successfully produced 7.56 g L−1L-sorbose. The whole-cell transformation of formaldehyde and dihydroxyacetone resulted in 252 g L−1 (2.21 M) L-erythrulose with a productivity of 126 g L−1 h−1, which is the highest value reported to date.