Role of hydrogen metabolism in the regulation of carbon and electron flow in Propionispira arboris
Biochemical and physiological studies documented the function of hydrogenase in catabolic processes linked to propionic acid production and in anabolic processes linked to nitrogen fixation. P. arboris was shown by /sup 14/C radio-tracer, /sup 13/C NMR, and enzyme activity analysis to produce propionic acid via the methylmalonyl CoA pathway with fumarate reductase accounting for the final redox reaction of catabolism. Key dehydrogenase activity levels varied in response to the energy source used for growth with high levels of hydrogenase, lactate and glyceraldehyde 3-phosphate dehydrogenase expressed in the presence of H/sub 2/, lactate, or glucose respectively. The presence of hydrogen in culture medium altered the fermentation of glucose, lactate, or fumarate from a propionate to acetate ratio of 2:1 to nearly a homopropionate fermentation as a consequence of H/sub 2/ consumption via hydrogenase. /sup 14/C tracer, electron paramagnetic resonance studies, and enzyme activity analysis demonstrated the H/sub 2/ dependent homopropionate fermentation was caused by the competitive inhibition of pyruvate oxidation as a consequence of hydrogenase over-reducing the common electron acceptor, a 2(4Fe-4S) ferredoxin.
- Research Organization:
- Wisconsin Univ., Madison (USA)
- OSTI ID:
- 5207847
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
CARBON 13
CARBON 14 COMPOUNDS
CARBON ISOTOPES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
ELECTRON TRANSFER
ELEMENTS
ENZYME ACTIVITY
ENZYMES
EVEN-ODD NUCLEI
HYDROGEN
HYDROGENASES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
MAGNETIC RESONANCE
METABOLISM
MONOCARBOXYLIC ACIDS
NITROGEN FIXATION
NMR SPECTRA
NONMETALS
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PROPIONIC ACID
REDOX REACTIONS
RESONANCE
SPECTRA
STABLE ISOTOPES
SYNTHESIS
TRACER TECHNIQUES