In vivo NMR analysis of the influence of pyruvate decarboxylase and alcohol dehydrogenase of Zymomonas mobilis on the anaerobic metabolism of Escherichia coli
- California Inst. of Tech., Pasadena (United States)
Phosphorus-31 NMR studies of Escherichia coli expressing cloned pyruvate decarboxylase (pdc) and alcohol dehydrogenase (adh) genes from Zymomonas mobilis revealed significant changed in the concentration of intracellular metabolites. The intracellular concentrations of phosphate, sugar phosphates, NAD(H), NTP, NDP, and UDPG of the strain HB101 expressing pdc, adh, or both genes were analyzed at quasi steady state during the anaerobic catabolism of glucose. The evolution of the intracellular pH and extracellular pH during glucose consumption showed a constant value of {Delta}pH equal to extracellular pH during glucose consumption showed a constant value of {Delta}pH equal to 0.2 pH unit that did not depend on the expression of Zymomonas genes. The strains expressing PDC only exhibited greatest changes in the intracellular composition with significantly decreased inorganic phosphate, NAD(H), NTP, and UDPG and significantly increased sugar phosphates. Analysis of the fermentation products during the NMR experiments provided further information about the physiological changes observed in the cells. Two plasmid effects of the host metabolism are reported, one induced by the plasmid utilized as control (pUC19), and the other induced by the expression of the pet operon. In both cases an enhancement of the glucose uptake rate was observed. Although the plasmid carrying adh induces a rapid metabolic inhibition, the expression of pdc does not. The expression of pdc and adh together showed a physiological enhancement that is attributable not to effects on external pH rather to the effect of the switch in pathways from mixed acid to ethanol fermentation.
- OSTI ID:
- 5963204
- Journal Information:
- Biotechnology Progress; (United States), Vol. 7:4; ISSN 8756-7938
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ESCHERICHIA COLI
GENETIC ENGINEERING
ETHANOL
BIOSYNTHESIS
ALCOHOL DEHYDROGENASE
BIOLOGICAL PATHWAYS
DECARBOXYLASES
DNA-CLONING
FERMENTATION
GENE OPERONS
GENES
METABOLISM
PLASMIDS
RECOMBINANT DNA
ZYMOMONAS MOBILIS
ALCOHOLS
BACTERIA
BIOCONVERSION
BIOTECHNOLOGY
CARBON-CARBON LYASES
CARBOXY-LYASES
CELL CONSTITUENTS
CLONING
DNA
DNA HYBRIDIZATION
ENZYMES
HEMIACETAL DEHYDROGENASES
HYBRIDIZATION
HYDROXY COMPOUNDS
LYASES
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PROTEINS
SYNTHESIS
090900* - Biomass Fuels- Processing- (1990-)