Comparison of lactate dehydrogenase and acetolactate synthase deficient mutants of Klebsiella pneumonia TWO on 1, 3-propanediol production

Abstract

The microbiological production of 1, 3-propanediol (1, 3-PDO) has attracted much attention as an alternative way to produce important platform chemical from glycerol. Metabolic engineering has emerged as a powerful tool to enhance the production of 1, 3-PDO by multiple strategies. Knoking-out lactate dehydrogenase (encoded by ldh gene) and acetolactate synthase (encoded by budB gene) have been extensively studied as a competitor on 1, 3-PDO production. However, there is a lack of information which comparing the profiles between ldh and budB gene deficient mutants on glycerol metabolism. An inactivation of ldh and budB gene in Klebsiella pneumoniae TWO were successfully constructed by insertion of a spectinomycin-streptomycin resistance marker. All mutants were incubated in flask experiments with 20 g/l glycerol over 30 h. Compared with the wildtype and mutant strains, the highest productivity of 1, 3-PDO was produced by budB inactivation (8.71 g/l), whereas reduced ldh activity decreased 11% in the productivity of 1, 3-PDO (6.93 g/l) and led to the 29% increase of ethanol production (2.32 g/l). These result suggested that the activity of budB could be a key factor on the enhancement of 1, 3-PDO production between 2, 3-BDO and lactate production, as the competitor by-products