Natural microbes that produce 1,3-Propanediol are Klebsiella, Clostridia, Citrobacter, Enterobacter and Lactobacilli. They all use glycerol as a carbon source and produce 1,3 PDO through 3-hydroxypropionaldehyde route
using glycerol dehydratase enzymes and 1,3-propanediol oxidoreductase enzymes. The biggest constraint for microbial production of 1,3 PDO is low yield and productivity which is due to multiple reasons including:
as low cell density, irreversible inhibition of glycerol dehydratase enzyme with glycerol, and requirement of speciality ingredients such as vitamins.
Though the use of waste glycerol from biofuel industry is highly advocated, its usage will cause more complications due to microbial inhibition with the presence of methanol, surfactants, and free fatty acids.