Production of 1,3-propanediol by Clostridium beijerinckii DSM 791 from crude glycerol and corn steep liquor: Process optimization and metabolic engineering

1,3-Propanediol (1,3-PDO) production from crude glycerol, a byproduct from biodiesel manufacturing, by Clostridium beijerinckii DSM 791 was studied with corn steep liquor as an inexpensive nitrogen source replacing yeast extract in the fermentation medium. A stable, long-term 1,3-PDO production from glycerol was demonstrated with cells immobilized in a fibrous bed bioreactor operated in a repeated batch mode, which partially circumvented the 1,3-PDO inhibition problem. The strain was then engineered to overexpress Escherichia coli gldA encoding glycerol dehydrogenase (GDH) and dhaKLM encoding dihydroxyacetone kinase (DHAK), which increased 1,3-PDO productivity by 26.8-37.5% compared to the wild type, because of greatly increased specific growth rate (0.25-0.40 h (1) vs. 0.13-0.20 h (1) for the wild type). The engineered strain gave a high 1,3-PDO titer (26.1 g/L), yield (0.55 g/g) and productivity (0.99 g/L.h) in fed-batch fermentation. Overexpressing GDH and DHAK was thus effective in increasing 1,3-PDO production from glycerol. (C) 2016 Elsevier Ltd. All rights reserved.