Metabolic engineering of Escherichia coli for de novo biosynthesis of vitamin B12

The only known source of vitamin B 12 (adenosylcobalamin) is from bacteria and archaea. Here, using genetic and metabolic engineering, we generate an Escherichia coli strain that produces vitamin B 12 via an engineered de novo aerobic biosynthetic pathway. In vitro and/or in vivo analysis of genes involved in adenosylcobinamide phosphate biosynthesis from Rhodobacter capsulatus suggest that the biosynthetic steps from co(II)byrinic acid a,c-diamide to adocobalamin are the same in both the aerobic and anaerobic pathways. Finally, we increase the vitamin B 12 yield of a recombinant E. coli strain by more than ∼250-fold to 307.00 µg g −1 DCW via metabolic engineering and optimization of fermentation conditions. Beyond our demonstration of E. coli as a microbial biosynthetic platform for vitamin B 12 production, our study offers an encouraging example of how the several dozen proteins of a complex biosynthetic pathway can be transferred between organisms to facilitate industrial production.