A process is provided for the bioconversion of a carbon substrate to 1,3-propanediol by a single organism utilizing microorganisms, such as, Citrobacter, Enterobacter, Clostridium, Klebsiella, Aerobacter, Lactobacillus, Aspergillus, Saccharomyces, Zygosaccharomyces, Pichia, Kluyveromyces, Candida, Hansenula, Debaryomyces, Mucor, Torulopsis, Methylobacter, Escherichia, Salmonella, Bacillus, Streptomyces and Pseudomonas, containing the genes encoding for an active glycerol or diol dehydratase enzyme by contacting these organisms with a carbon substrate under the appropriate fermentation conditions. Specifically, Citrobacter and, Klebsiella provide the source of exogenous genes for such active dehydratase enzyme.