The invention concerns a method for preparing 1,3-propanediol from a carbon-containing substance, said method comprising a step which consists in culturing a recombinant micro-organism not producing coenzyme B12 in the absence of coenzyme B12 or one of its precursors. The invention also concerns a nucleic acid coding for a glycerol dehydratase whereof the catalytic activity is independent of the presence of coenzyme B12 or one of its precursors and a nucleic acid coding for a 1,3-propanol dehydrogenase intervening in the synthesis of 1,3-propanediol. The invention further concerns recombinant vectors and host cells comprising said nucleic acids and the polypeptides coded by the latter.