Methods and Material: 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 further optimization of the fermentation protocol.
Results: Evaluating crude glycerol samples from various biodiesel productions, min 85 g l-1 of 1,3-propanediol were obtained with a productivity of min 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 min 75 g l-1 1,3-propanediol and a productivity of 0.36 g l-1 h-1. Thereafter further optimization of nutrients shows significant improvement of productivity of up to two times compared to previous.
Conclusions: 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.