Construction of an efficient Escherichia coli whole-cell biocatalyst for d-mannitol production

Mannitol is a six carbon sugar alcohol that finds applications in the pharmaceutical and food industries. A novel Escherichia coli strain capable of converting d-glucose to d-mannitol has been constructed, wherein native mannitol-1-phosphate dehydrogenase (MtlD) and codon-optimized Eimeria tenella mannitol-1-phosphatase (M1Pase) have been overexpressed. Codon-optimized Pseudomonas stutzeri phosphite dehydrogenase (PtxD) was overexpressed for cofactor (NADH) regeneration with the concomitant oxidation of phosphite to phosphate. Whole-cell biotransformation using resting cells in a medium containing d-glucose and equimolar sodium phosphite resulted in d-mannitol yield of 87 mol%. Thus, production of an industrially relevant biochemical without using complex media components and elaborate process control mechanisms has been demonstrated.