1,3 propanediol has been identified as a key- substance chemical in production of bio-plastics. The current industrial biotechnological process is based on glucose as the primary feedstock, thus weakening the commercial competitiveness. A process to convert crude glycerol, directly derived from biodiesel production, to 1,3 propanediol was the primary goal of invention.
Methods and Materials
A non- pathogen bacterium, Lactobacillus diolivorans, was identified as a favorable organism for industrial 1,3-propanediol production. Initial conversion and productivity rates of the wild strain and efficiency in the conversion of crude glycerol were further increased by genetic engineering and optimization of the fermentation protocol. The application of lignocellulosic hydrolysates as the sole carbohydrate source for biomass formation was evaluated.
Results
Evaluating crude glycerol samples from various biodiesel productions, 85 g l-1 of 1,3-propanediol were obtained with a productivity of 0.45 g l-1 h-1 in feed-batch cultivation. No inhibitory effects of crude glycerol on growth of the microorganism or production rate could be observed.
The use of lignocellulosic hydrolysates as sole carbon source, containing the potential inhibitors furfural and 5-hydroxymethylfurfural at concentrations of 0.7 g l-1 and 0.3 g l-1, did not show a significant decrease of conversion rates and result to 75 g l-1 1,3-propanediol and a productivity of 0.36 g l-1 h-1 .
Conclusions
A non- pathogen, genetically modified Lactobacillus diolivorans bio-transforms effectively and stable crude glycerol to 1,3 propanediol and lignocellulosic hydrolysates as the sole carbohydrate source for biomass grow as a commercially viable alternative to current production protocols.