We have recently shown that the glycerol dehydratase of C. butyricum VPI1718 is not stimulated by Coenzyme B12 and is extremely oxygen sensitive which suggests that it is a coenzyme-B12 independent enzyme. We have cloned, sequenced and characterized from a molecular point of view the genes encoding the glycerol dehydratase and the 1, 3 propanediol dehydrogenase of C. butyricumVPI 1718. By both heterologous expression and biochemical characterization, we have demonstrated that this glycerol dehydratase is "coenzyme B₁₂ independent". This unique enzyme belongs to a new family of glycerol dehydratase that has never been described so far. By heterologous expression of this new dehydratase and the 1, 3 propanediol dehydrogenase and by introducing defined mutations in the central metabolism of C. acetobutylicum, we obtained a recombinant strain that possesses the best yield and productivity for glycerol conversion to 1, 3 propanediol.

This new enzyme allow the development of an economical “vitamin B12 free” biological process for the continuous production of 1, 3 propanediol from industrial glycerine.