Monday, May 2, 2011
Grand Ballroom C-D, 2nd fl (Sheraton Seattle)
3-Hydroxypropionic acid (3-HP) is an important three-carbon platform chemical for production of several commodity and specialty chemicals. For the biosynthesis of 3-HP from glycerol, two key enzymes of glycerol dehydratase and aldehyde dehydrogenase are involved. In this study, the dhaB gene cluster coding for a novel glycerol dehydratase (DHAB) and the dhaR gene cluster coding for reactivation factor of glycerol dehydratase (DHAR) were cloned from Lactobacillus brevis ATCC 367, and the aldehyde dehydrogenase (ALDH) gene was cloned from Escherichia coli K12 for the production of 3-HP from glycerol. Recombinant E. coli BL21 star (DE3)/pELDRR+pCEa expressing DHAB-DHAR and ALDH was constructed. A fed-batch fermentation of the recombinant E. coli strain grown in a pH-stat mode resulted in 14.3 g/L 3-HP concentration, 0.26 g/L-hr its productivity and a 3-HP yield of 0.14 g/g glycerol. The glpK gene coding for glycerol kinase which catalyzes the conversion of glycerol to glycerol-3-phosphate was deleted in the recombinant E. coli to improve 3-HP production yield further. As a result, 29.3 g/L 3-HP concentration, 1.33 g/L-hr productivity and a 3-HP yield of 0.62 mol/mol glycerol were obtained in a fed-batch fermentation of the glpK-deleted recombinant E. coli strain expressing DHAB-DHAR and ALDH.