Comparison of unitrophic and mixotrophic substrate metabolism by an acetate-adapted strain of Methanosarcina barkeri
We examined the unitrophic metabolism of acetate and methanol individually and the mixotrophic utilization of these compounds by using detailed /sup 14/C-labeled tracer studies in a strain of Methanosarcina barkeri adapted to grow on acetate as the sole carbon and energy source. The substrate consumption rate and methane production rate were significantly lower on acetate alone than during the unitrophic or mixotrophic metabolism of methanol. Cell yields (in grams per mole of substrate) were identical during exponential growth on acetate and exponential growth on methanol. During unitrophic metabolism of acetate, the methyl moiety accounted for the majority of the CH/sub 4/ produced, but 14% of the CO/sub 2/ generated originated from the methyl moiety. This correlated with the concurrent reduction of equivalent amounts of the C-1 of acetate to CH/sub 4/. /sup 14/CH/sub 4/ was also produced from added /sup 14/CO/sub 2/, although to a lesser extent than from reduction of the C-1 of acetate. During mixotrophic metabolism, methanol and acetate were catabolized simultaneously. The rates of /sup 14/CH/sub 4/ and /sup 14/CO/sub 2/ generation from (2-/sup 14/C)acetate were logarithmic and higher in mixotrophic than in unitrophic cultures at substrate concentrations of 50 mM. A comparison of the oxidoreductase activities in cell extracts of the acetate-adapted strain grown on acetate and of strain MS grown on methanol or on H/sub 2/ plus CO/sub 2/ indicated that the pyruvate, ..cap alpha..-ketoglutarate, and isocitrate dehydrogenase activities remained constant, whereas the CO dehydrogenase activity was significantly higher (5,000 nmol/min per mg of protein) in the acetate-adapted strain. These results suggested that a significant intramolecular redox pathway is possible for the generation of CH/sub 4/ from acetate, that energy metabolism from acetate by M. barkeri is not catabolite repressed by methanol, and that the acetate-adapted strain is a metabolic mutant with depressed CO dehydrogenase activity.
- Research Organization:
- University of Wisconsin, Madison
- OSTI ID:
- 5732116
- Journal Information:
- J. Bacteriol.; (United States), Vol. 149:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ACETATES
METABOLISM
CARBON 14 COMPOUNDS
UPTAKE
METHANE
PRODUCTION
METHANOGENIC BACTERIA
COMPARATIVE EVALUATIONS
PRODUCTIVITY
METHANOL
BIOLOGICAL PATHWAYS
CARBON DIOXIDE
CATABOLISM
ENZYME ACTIVITY
EXPERIMENTAL DATA
GROWTH
MUTANTS
OXIDOREDUCTASES
REDOX REACTIONS
SUBSTRATES
TRACER TECHNIQUES
ALCOHOLS
ALKANES
BACTERIA
CARBON COMPOUNDS
CARBON OXIDES
CARBOXYLIC ACID SALTS
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
ENZYMES
HYDROCARBONS
HYDROXY COMPOUNDS
INFORMATION
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MICROORGANISMS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
550700* - Microbiology
550500 - Metabolism