Metabolic engineering of 1,2-propanediol production from cellobiose using beta-glucosidase-expressing E. coli

Microbial 1,2-propanediol production using renewable feedstock is a promising method for the sustainable production of value-added fuels and chemicals. We demonstrated the metabolically engineered Escherichia coli for improvement of 1,2-propanediol production using glucose and cellobiose. The deletion of competing pathways improved 1,2-propanediol production. To reduce carbon flux toward downstream glycolysis, the phosphotransferase system (PTS) was inactivated by ptsG gene deletion. The resultant strain, GL3/PD, produced 1.48 ± 0.01 g/L of 1,2-propanediol from 20 g/L of glucose. A sugar supply was engineered by coexpression of β-glucosidase (BGL). The strain expressing BGL produced 1,2-propanediol from cellobiose at a concentration of 0.90 ± 0.11 g/L with a yield of 0.15 ± 0.01 g/g glucose (cellobiose 1 g is equal to glucose 1.1 g). As cellobiose or cellooligosaccharides a carbon source, the feasibility of producing 1,2-propanediol using an E. coli strain engineered for β-glucosidase expression are demonstrated.