Analysis of the Growth and Metabolites of a Pyruvate Dehydrogenase Complex- Deficient Mutant in a Glycerol-Based Medium.

To determine the role of pyruvate dehydrogenase complex (PDHC) in , the growth and metabolism of PDHC-deficient mutant in glycerol-based medium were analyzed and compared with those of other strains. Under aerobic conditions, the PDHC activity was fourfold higher than that of pyruvate formate lyase (PFL), and blocking of PDHC caused severe growth defect and pyruvate accumulation, indicating that the carbon flux through pyruvate to acetyl coenzyme A mainly depended on PDHC. Under anaerobic conditions, although the PDHC activity was only 50% of that of PFL, blocking of PDHC resulted in more growth defect than blocking of PFL.

Deleting pck improves growth and suppresses by-product formation during 1,3-propanediol fermentation by Klebsiella pneumoniae.

Aims: To investigate the role of phosphoenolpyruvate (PEP) carboxylation in cell metabolism in Klebsiella pneumoniae.

Methods And Results: The effects of deleting pck, which encodes PEP carboxykinase (PCK), and/or ppc, which encodes PEP carboxylase (PPC), on growth, enzyme activity and metabolite formation of Kl. pneumoniae were investigated.

Deletion of poxB, pta, and ackA improves 1,3-propanediol production by Klebsiella pneumoniae.

To date, few studies have focused on reducing the toxic by-product acetate during 1,3-propanediol production by Klebsiella pneumoniae. In this study, the effects of deleting the poxB, pta, and ackA genes, which are involved in the two main acetate synthesis pathways, on cell growth and 1,3-propanediol production were investigated. Although acetate synthesis via pyruvate oxidase (PoxB, encoded by poxB) generally seems unnecessary and wasteful, PoxB was shown to play an important role in K.