Background: As a kind of rare sugar alcohol, allitol has important application values in food and medication. In addition, it can be used as a key substrate to produce other d/l-rare sugars. Allitol can be effectively produced by the resting-cell biotransformation method.

Results: Two recombinant Escherichia coli strains, one simultaneously expressing ribitol dehydrogenase (RDH) and formate dehydrogenase (FDH) in fusion (fusion expression strain for short) and the other expressing the above two enzymes individually (individual expression strain for short), were respectively constructed and used for allitol bioproduction. The produced allitol was confirmed by HPLC, mass spectrometry, and polarimetry. The individual expression strain had higher activity, which produced 58.5 g/L allitol from 90 g/L d-allulose (also named d-psicose) in 1 h with an allitol productivity of 58.5 g/L/h under optimized conditions.

Conclusions: The constructed individual expression strain had the highest allitol productivity among the reports. The production process developed in this study was simple, highly efficient, and had the potential for mass production of allitol.